A period is all about defining when something begins and ends. Class periods usually last about forty-five minutes. Following the last food fight, there was a period of relative peace in the school.

You know that dot at the end of a sentence? That's a period too. It means the sentence is over. In sports, games are often divided into playing periods: an ice hockey game, for example, has three periods. If you're a dinosaur buff, you know that this word can also refer to expanses of geologic time. The stegosaurus lived during the Jurassic period, for example, while the Tyrannosaurus rex and triceratops lived during the Cretaceous period.

Primary Meanings of period

an amount of time
a punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations
Full Definitions of period

n an amount of time

“a time period of 30 years”
“hastened the period of time of his recovery”
“Picasso's blue period
period of time, time period
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Bronze Age
(archeology) a period between the Stone and Iron Ages, characterized by the manufacture and use of bronze tools and weapons
Iron Age
(archeology) the period following the Bronze Age; characterized by rapid spread of iron tools and weapons
Stone Age
(archeology) the earliest known period of human culture, characterized by the use of stone implements
Eolithic Age
the earliest part of the Stone Age marked by the earliest signs of human culture
Paleolithic Age
second part of the Stone Age beginning about 750,00 to 500,000 years BC and lasting until the end of the last ice age about 8,500 years BC
Lower Paleolithic
the oldest part of the Paleolithic Age with the emergence of the hand ax; ended about 120,000 years ago
Middle Paleolithic
the time period of Neanderthal man; ended about 35,000 years BC
Upper Paleolithic
the time period during which only modern Homo sapiens was known to have existed; ended about 10,000 years BC
middle part of the Stone Age beginning about 15,000 years ago
Neolithic Age
latest part of the Stone Age beginning about 10,000 BC in the Middle East (but later elsewhere)
Great Schism
the period from 1378 to 1417 during which there were two papacies in the Roman Catholic Church, one in Rome and one in Avignon
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test period, trial period
a period of time during which someone or something is tested
time frame
a time period during which something occurs or is expected to occur
an indefinite period of time
a period of time when something (as a machine or factory) is not operating (especially as a result of malfunctions)
a period of time when something (as a machine or factory) is functioning and available for use
work time
a time period when you are required to work
time off
a time period when you are not required to work
a period of illness
hospitalisation, hospitalization
a period of time when you are confined to a hospital
travel time
a period of time spent traveling
a more or less definite period of time now or previously present
an indefinite period (usually marked by specific attributes or activities)
elapsed time
the time that elapses while some event is occurring
continuance, duration
the period of time during which something continues
calendar week, week
a period of seven consecutive days starting on Sunday
the middle of a week
field day
a time of unusual pleasure and success
life, life-time, lifespan, lifetime
the period during which something is functional (as between birth and death)
the period between birth and the present time
the period from the present until death
millenary, millennium
a span of 1000 years
bimillenary, bimillennium
a span of 2000 years
the period of time during which a place or position or nation is occupied
a earlier period in someone's life (especially one that they have reason to keep secret)
shelf life
the length of time a packaged food or drug will last without deteriorating
time period following childbirth when the mother's uterus shrinks and the other functional and anatomic changes of pregnancy are resolved
the period following birth during which milk is secreted
time of life
a period of time during which a person is normally in a particular life state
calendar day, civil day
a day reckoned from midnight to midnight
a day or period of time set aside for feasting and celebration
day, daylight, daytime
the time after sunrise and before sunset while it is light outside
forenoon, morn, morning, morning time
the time period between dawn and noon
dark, night, nighttime
the time after sunset and before sunrise while it is dark outside
the time between sunset and midnight
the period spent sleeping
a period of ignorance or backwardness or gloom
the period immediately before something
the early part of night (from dinner until bedtime) spent in a special way
hebdomad, week
any period of seven consecutive days
fortnight, two weeks
a period of fourteen consecutive days
a time period usually extending from Friday night through Sunday; more loosely defined as any period of successive days including one and only one Sunday
Indian summer, Saint Martin's summer
a period of unusually warm weather in the autumn
the period of time that it takes for a planet (as, e.g., Earth or Mars) to make a complete revolution around the sun
school, school day, schooltime
the period of instruction in a school; the time period when school is in session
twelvemonth, year, yr
a period of time containing 365 (or 366) days
a period of time occupying a regular part of a calendar year that is used for some particular activity
half a year; a period of 6 months
a period of 2 months
one of the four-year intervals between Olympic Games; used to reckon time in ancient Greece for twelve centuries beginning in 776 BC
a period of five years
decade, decennary, decennium
a period of 10 years
a period of 100 years
a period of four years
a period of five years
a period of 50 years
a period of 25 years
a fourth part of a year; three months
phase of the moon
a time when the Moon presents a particular recurring appearance
the period of time taken by a particular planet (e.g. Mars) to make a complete rotation on its axis
calendar month, month
one of the twelve divisions of the calendar year
the middle part of January
the middle part of February
the middle part of March
the middle part of April
the middle part of May
the middle part of June
the middle part of July
the middle part of August
the middle part of September
the middle part of October
the middle part of November
the middle part of December
time limit
a time period within which something must be done or completed
a limited period of time
a period of three months; especially one of the three three-month periods into which human pregnancy is divided
a special and memorable period
silly season
a time usually late summer characterized by exaggerated news stories about frivolous matters for want of real news
Golden Age
(classical mythology) the first and best age of the world, a time of ideal happiness, prosperity, and innocence; by extension, any flourishing and outstanding period
silver age
(classical mythology) the second age of the world, characterized by opulence and irreligion; by extension, a period secondary in achievement to a golden age
bronze age
(classical mythology) the third age of the world, marked by war and violence
iron age
(classical mythology) the last and worst age of the world
Platonic year, great year
time required for one complete cycle of the precession of the equinoxes, about 25,800 years
regulation time
(sports) the normal prescribed duration of a game
extra time, overtime
playing time beyond regulation, to break a tie
season, time of year
one of the natural periods into which the year is divided by the equinoxes and solstices or atmospheric conditions
canicular days, canicule, dog days
the hot period between early July and early September; a period of inactivity
the middle of winter
a recurrent time marked by major holidays
a period of the year marked by special events or activities in some field
age, long time, years
a prolonged period of time
long haul, long run
a period of time sufficient for factors to work themselves out
drought, drouth
a prolonged shortage
epoch, era
a period marked by distinctive character or reckoned from a fixed point or event
the normal time between successive generations
prehistoric culture, prehistory
the time during the development of human culture before the appearance of the written word
a period during which something or somebody is dominant or powerful
the continuous period of time during which something (a machine or a factory) operates or continues in operation
early days, youth
an early period of development
an opening time period
a later concluding time period
a period of time considered as a resource under your control and sufficient to accomplish something
nap, sleep
a period of time spent sleeping
lease, term of a contract
the period of time during which a contract conveying property to a person is in effect
half life, half-life
the time required for something to fall to half its initial value (in particular, the time for half the atoms in a radioactive substance to disintegrate)
lunar time period, tide
there are usually two high and two low tides each day
phase, stage
any distinct time period in a sequence of events
occurring in more than one stage
the period during which someone (especially a guard) is on duty
a period of time during which there is no war
a period of time during which there is armed conflict
duty tour, enlistment, hitch, term of enlistment, tour, tour of duty
a period of time spent in military service
the early (usually calm and harmonious) period of a relationship; business or political
a 15-year cycle used as a chronological unit in ancient Rome and adopted in some medieval kingdoms
prohibition, prohibition era
the period from 1920 to 1933 when the sale of alcoholic beverages was prohibited in the United States by a constitutional amendment
incubation period
the period between infection and the appearance of symptoms of the disease
rainy day
a (future) time of financial need
noviciate, novitiate
the period during which you are a novice (especially in a religious order)
bloom, blossom, efflorescence, flower, flush, heyday, peak, prime
the period of greatest prosperity or productivity
running time
the length of time that a movie or tv show runs
clotting time
the time it takes for a sample of blood to clot; used to diagnose some clotting disorders
air alert
the time period during which military and civilian agencies are prepared for an enemy air attack
question time
a period during a parliamentary session when members of British Parliament may ask questions of the ministers
real time
(computer science) the time it takes for a process under computer control to occur
real time
the actual time that it takes a process to occur
study hall
a period of time during the school day that is set aside for study
the period of time permitted by commercial usage for the payment of a bill of exchange (especially a foreign bill of exchange)
the time period that is considered best for starting or finishing something
harvest, harvest time
the season for gathering crops
haying, haying time
the season for cutting and drying and storing grass as fodder
the final stage of the prophase of meiosis
the fourth stage of the prophase of meiosis
the first stage of the prophase of meiosis
the third stage of the prophase of meiosis
phase of cell division
a stage in meiosis or mitosis
the second stage of the prophase of meiosis
uptime is 24 hours a day 7 days a week
a period of time assigned for work
face time
work time spent at the location of or in the presence of other people
compensatory time
time off that is granted to a worker as compensation for working overtime
contemporary world, modern times, modern world, present times
the circumstances and ideas of the present age
Roman times
the time period during which Rome dominated Europe
some point or period in time
a time when coldness (or some other quality associated with death) is intense
hard times
a time of difficulty
time passed in a particular bodily form
OWLT, one-way light time
the elapsed time it takes for light (or radio signals) to travel between the Earth and a celestial object
RTLT, round-trip light time
the elapsed time it takes for a signal to travel from Earth to a spacecraft (or other body) and back to the starting point
the time taken to traverse a measured course
a period of dullness or boredom (especially in a work of literature or performing art)
residence time
the period of time spent in a particular place
the complete duration of something
stint, stretch
an unbroken period of time during which you do something
time scale
an arrangement of events used as a measure of duration
note value, time value, value
(music) the relative duration of a musical note
week, workweek
hours or days of work in a calendar week
the recurring hours when you are not sleeping (especially those when you are working)
work done in addition to regular working hours
turnaround, turnaround time
time need to prepare a vessel or ship for a return trip
free time, spare time
time available for hobbies and other activities that you enjoy
day off
a day when you are not required to work
leisure, leisure time
time available for ease and relaxation
leave, leave of absence
the period of time during which you are absent from work or duty
days, years
the time during which someone's life continues
afterlife, hereafter
life after death
the period of finest development, happiness, or beauty
age, eld
a time of life (usually defined in years) at which some particular qualification or power arises
neonatal period
the first 28 days of life
babyhood, early childhood, infancy
the early stage of growth or development
anal phase, anal stage
(psychoanalysis) the second sexual and social stage of a child's development during which bowel control is learned
genital phase, genital stage
(psychoanalysis) the fifth sexual and social stage in a person's development occurring during adolescence; interest focuses on sexual activity
latency period, latency phase, latency stage
(psychoanalysis) the fourth period (from about age 5 or 6 until puberty) during which sexual interests are supposed to be sublimated into other activities
oral phase, oral stage
(psychoanalysis) the first sexual and social stage of an infant's development; the mouth is the focus of the libido and satisfaction comes from suckling and chewing and biting
phallic phase, phallic stage
(psychoanalysis) the third stage in a child's development when awareness of and manipulation of the genitals is supposed to be a primary source of pleasure
the time of person's life when they are a child
schooldays, schooltime
the time of life when you are going to school
the time of life between childhood and maturity
the time period between the beginning of puberty and adulthood
a period of two years immediately prior to the onset of puberty when growth and changes leading to sexual maturity occur
puberty, pubescence
the time of life when sex glands become functional
the time of life between the ages of 12 and 20
mid-twenties, twenties
the time of life between 20 and 30
the decade from 1900 to 1909
the decade from 1530 to 1539
1920s, twenties
the decade from 1920 to 1929
the decade from 1820 to 1829
mid-thirties, thirties, thirty-something
the time of life between 30 and 40
1930s, thirties
the decade from 1930 to 1939
the decade from 1830 to 1839
forties, mid-forties
the time of life between 40 and 50
1940s, forties
the decade from 1940 to 1949
the decade from 1840 to 1849
fifties, mid-fifties
the time of life between 50 and 60
1950s, fifties
the decade from 1950 to 1959
the decade from 1850 to 1859
the decade from 1750 to 1759
mid-sixties, sixties
the time of life between 60 and 70
1960s, sixties
the decade from 1960 to 1969
the decade from 1860 to 1869
the decade from 1760 to 1769
golden years
the time of life after retirement from active work
mid-seventies, seventies
the time of life between 70 and 80
1970s, seventies
the decade from 1970 to 1979
the decade from 1870 to 1879
the decade from 1770 to 1779
eighties, mid-eighties
the time of life between 80 and 90
1980s, eighties
the decade from 1980 to 1989
1880s, eighties
the decade from 1880 to 1889
the decade from 1780 to 1789
mid-nineties, nineties
the time of life between 90 and 100
1990s, nineties
the decade from 1990 to 1999
1890s, nineties
the decade from 1890 to 1899
the decade from 1790 to 1799
bloom, bloom of youth, salad days
the best time of youth
adulthood, maturity
the period of time in your life after your physical growth has stopped and you are fully developed
the time of a man's life prior to marriage
middle age
the time of life between youth and old age (e.g., between 40 and 60 years of age)
the time of a woman's life when she is a widow
age, eld, geezerhood, old age, years
a late time of life
the last few hours before death
a day assigned to a particular purpose or observance
the particular day, month, or year (usually according to the Gregorian calendar) that an event occurred
church festival, religious festival
a festival having religious significance
day of the week
any one of the seven days in a week
the part of the day between noon and evening
the middle part of the afternoon
eve, even, evening, eventide
the latter part of the day (the period of decreasing daylight from late afternoon until nightfall)
any night of the week except Saturday or Sunday
week from Monday
a time period of a week or more
rag, rag week
a week at British universities during which side-shows and processions of floats are organized to raise money for charities
Christian year, church year
the year in the ecclesiastical calendar; especially feast days and special seasons
Revolutionary calendar month
a month in the Revolutionary calendar
Holy Week, Passion Week
the week before Easter
Holy Year
(Roman Catholic Church) a period of remission from sin (usually granted every 25 years)
New Year
the calendar year just begun
the season of Michaelmas
the season of Lammas
the Easter season
the season of Epiphany
the season of All Saints' Day
Christmas, Christmastide, Christmastime, Noel, Yule, Yuletide
period extending from Dec. 24 to Jan. 6
anomalistic year
time of the earth's revolution from perihelion to perihelion again; 365 days and 6 hr and 13 min and 53.1 sec
365 days, common year
a year that is not a leap year
366 days, bissextile year, intercalary year, leap year
in the Gregorian calendar: any year divisible by 4 except centenary years divisible by 400
off year
a year in which no major political elections are held
off year
a year in which productivity is low or inferior
calendar year, civil year
the year (reckoned from January 1 to December 31) according to Gregorian calendar
astronomical year, equinoctial year, solar year, tropical year
the time for the earth to make one revolution around the sun, measured between two vernal equinoxes
lunar year
a period of 12 lunar months
financial year, fiscal year
any accounting period of 12 months
academic year, school year
the period of time each year when the school is open and people are studying
(Latin) year
the 15th century in Italian art and literature
twentieth century
the century from 1901 to 2000
new moon, new phase of the moon
the time at which the Moon appears as a narrow waxing crescent
the time at which the Moon is at first or last quarter when half its face is illuminated
full, full moon, full phase of the moon, full-of-the-moon
the time when the Moon is fully illuminated
lunar day
the period of time taken for the moon to make one full rotation on its axis (about 27.3 sidereal days)
sidereal year
the time for the earth to make one complete revolution around the sun, relative to the fixed stars
Gregorian calendar month
a month in the Gregorian calendar
Jewish calendar month
a month in the Jewish calendar
Islamic calendar month
any lunar month in the Muslim calendar
Hindu calendar month
any lunisolar month in the Hindu calendar
wedding night
the night after the wedding when bride and groom sleep together
(law) a time period after which suits cannot be brought
prison term, sentence, time
the period of time a prisoner is imprisoned
academic session, academic term, school term, session
the time during which a school holds classes
first trimester
time period extending from the first day of the last menstrual period through 12 weeks of gestation
second trimester
time period extending from the 13th to the 27th week of gestation
third trimester
time period extending from the 28th week of gestation until delivery
extra innings
overtime play until one team is ahead at the end of an inning; e.g. baseball
overtime period
a period of overtime play to resolve a tie; e.g. basketball
overtime play in order to break a tie; e.g. tennis and soccer
sudden death
(sports) overtime in which play is stopped as soon as one contestant scores; e.g. football and golf
autumn, fall
the season when the leaves fall from the trees
spring, springtime
the season of growth
summer, summertime
the warmest season of the year; in the northern hemisphere it extends from the summer solstice to the autumnal equinox
winter, wintertime
the coldest season of the year; in the northern hemisphere it extends from the winter solstice to the vernal equinox
growing season
the season during which a crop grows best
the time during which seeds should be planted
the time or season when sheep are sheared
holiday season
a time when many people take holidays
high season, peak season
the season when travel is most active and rates are highest
the season when travel is least active and rates are lowest
rainy season
one of the two seasons in tropical climates
dry season
one of the two seasons in tropical climates
a period prior to the beginning of the regular season which is devoted to training and preparation
baseball season
the season when baseball is played
basketball season
the season when basketball is played
exhibition season
the time before the regular games begin when football or baseball teams play practice games
fishing season
the season during which it is legal to catch fish
football season
the season when football is played
hockey season
the season when hockey is played
hunting season
the season during which it is legal to kill a particular species
social season
the season for major social events
theatrical season
the season when new plays are produced
the season including the four Sundays preceding Christmas
immediately preceding Lent
Lent, Lententide
a period of 40 weekdays from Ash Wednesday to Holy Saturday
Whitsun, Whitsuntide, Whitweek
Christian holiday; the week beginning on Whitsunday (especially the first 3 days)
month of Sundays
a time perceived as long
aeon, eon
an immeasurably long period of time
blue moon
a long time
year dot
as long ago as anyone can remember
a short time
patch, piece, spell, while
a period of indeterminate length (usually short) marked by some action or condition
bit, minute, mo, moment, second
an indefinitely short time
something transitory; lasting a day
an era of existence or influence
year of grace
any year of the Christian era
the year 2000 in the Gregorian calendar
any distinct period in history or in a person's life
age, historic period
an era of history having some distinctive feature
modern era
the present or recent times
reign of terror
any period of brutal suppression thought to resemble the Reign of Terror in France
press run, print run
the period that presses run to produce an issue of a newspaper
(computer science) the length of time it takes to execute a software program
space age
the age beginning with the first space travel; from 1957 to the present
beauty sleep
sleep before midnight
(pathology) the phase in the development of an infection between the time a pathogen enters the body and the time the first symptoms appear
fertile period, fertile phase
the time in the menstrual cycle when fertilization is most likely to be possible (7 days before to 7 days after ovulation)
menstrual phase
the phase of the menstrual cycle during which the lining of the uterus is shed (the first day of menstrual flow is considered day 1 of the menstrual cycle)
an annual phase of heightened sexual excitement in the males of certain large mammals (especially elephants); is associated with discharge from a gland between the eye and ear
luteal phase, secretory phase
the second half of the menstrual cycle after ovulation; the corpus luteum secretes progesterone which prepares the endometrium for the implantation of an embryo; if fertilization does not occur then menstrual flow begins
a stage of technological development or innovation
apogee, culmination
a final climactic stage
any time of new development
incumbency, tenure, term of office
the term during which some position is held
golden age
a time period when some activity or skill was at its peak
the duration of a monarch's or government's power
safe period
that time during a woman's menstrual cycle during which conception is least likely to occur (usually immediately before of after menstruation)
shibah, shiva, shivah
(Judaism) a period of seven days of mourning after the death of close relative
a trial period during which an offender has time to redeem himself or herself
a trial period during which your character and abilities are tested to see whether you are suitable for work or for membership
Type of:
fundamental measure, fundamental quantity
one of the four quantities that are the basis of systems of measurement

n the interval taken to complete one cycle of a regularly repeating phenomenon

orbit period
the time it takes to complete one full orbit around a celestial body
Type of:
interval, time interval
a definite length of time marked off by two instants

n a unit of geological time during which a system of rocks formed

geological period
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Quaternary period
last 2 million years
Tertiary period
from 63 million to 2 million years ago
Cretaceous period
from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants
Jurassic period
from 190 million to 135 million years ago; dinosaurs; conifers
Triassic period
from 230 million to 190 million years ago; dinosaurs, marine reptiles; volcanic activity
Permian period
from 280 million to 230 million years ago; reptiles
Carboniferous period
from 345 million to 280 million years ago
Upper Carboniferous period
from 310 million to 280 million years ago; warm climate; swampy land
Lower Carboniferous period
from 345 million to 310 million years ago; increase of land areas; primitive ammonites; winged insects
Devonian period
from 405 million to 345 million years ago; preponderance of fishes and appearance of amphibians and ammonites
Silurian period
from 425 million to 405 million years ago; first air-breathing animals
Ordovician period
from 500 million to 425 million years ago; conodonts and ostracods and algae and seaweeds
Cambrian period
from 544 million to about 500 million years ago; marine invertebrates
glacial epoch, glacial period, ice age
any period of time during which glaciers covered a large part of the earth's surface
Type of:
geologic time, geological time
the time of the physical formation and development of the earth (especially prior to human history)

n the monthly discharge of blood from the uterus of nonpregnant women from puberty to menopause

catamenia, flow, menses, menstruation, menstruum
hypermenorrhea, menorrhagia
abnormally heavy or prolonged menstruation; can be a symptom of uterine tumors and can lead to anemia if prolonged
abnormally light or infrequent menstruation
Type of:
discharge, emission, expelling
any of several bodily processes by which substances go out of the body

n (ice hockey) one of three divisions into which play is divided in hockey games

Type of:
division, part, section
one of the portions into which something is regarded as divided and which together constitute a whole

n a punctuation mark (.) placed at the end of a declarative sentence to indicate a full stop or after abbreviations

“in England they call a period a stop”
full point, full stop, point, stop
suspension point
(usually plural) one of a series of points indicating that something has been omitted or that the sentence is incomplete
Type of:
punctuation, punctuation mark
the marks used to clarify meaning by indicating separation of words into sentences and clauses and phrases

n the end or completion of something

“death put a period to his endeavors”
“a change soon put a period to my tranquility”
Type of:
end, ending
the point in time at which something ends

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