# ratio

A ratio is the relationship in quantity or degree between two things: “The ratio of men to women on the construction site was ten to one.” This means there were ten men present and one woman.

Use the word ratio when you want to make a comparison between two things. A ratio basically expresses a proportion. Often used in mathematics, the word ratio has many real world uses as well. This word is useful for everything from making salad dressing (an oil-to-vinegar ratio of three to one) to selecting a school for a child (consider the student-to-teacher ratio when making your decision).

Definitions of ratio
1

### n the relation between things (or parts of things) with respect to their comparative quantity, magnitude, or degree

Synonyms:
proportion
Type of:
magnitude relation, quantitative relation
a relation between magnitudes

### n the relative magnitudes of two quantities (usually expressed as a quotient)

Types:
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gross margin, margin of profit, profit margin
the ratio gross profits divided by net sales
abundance
(chemistry) the ratio of the total mass of an element in the earth's crust to the total mass of the earth's crust; expressed as a percentage or in parts per million
abundance
(physics) the ratio of the number of atoms of a specific isotope of an element to the total number of isotopes present
albedo, reflective power
the ratio of reflected to incident light
aspect ratio
the ratio of the width to the height of a tv picture
average
(sports) the ratio of successful performances to opportunities
breadth index, cephalic index, cranial index
ratio (in percent) of the maximum breadth to the maximum length of a skull
efficiency
the ratio of the output to the input of any system
facial index
the ratio (in percent) of the maximum width to the maximum height of the face
f number, focal ratio, speed, stop number
the ratio of the focal length to the diameter of a (camera) lens system
frequency, relative frequency
the ratio of the number of observations in a statistical category to the total number of observations
haematocrit, hematocrit, packed cell volume
the ratio of the volume occupied by packed red blood cells to the volume of the whole blood as measured by a hematocrit
I.Q., IQ, intelligence quotient
a measure of a person's intelligence as indicated by an intelligence test; the ratio of a person's mental age to their chronological age (multiplied by 100)
(aeronautics) the ratio of an external load to the weight of the aircraft (measured in g)
loss ratio
the ratio of the annual claims paid by an insurance company to the premiums received
Mach number
the ratio of the speed of a moving body to the speed of sound
magnification
the ratio of the size of an image to the size of the object
the ratio of the force exerted by a machine to the force applied to it
fuel consumption rate, gas mileage, gasoline mileage, mileage
the ratio of the number of miles traveled to the number of gallons of gasoline burned
betting odds, odds
the ratio by which one better's wager is greater than that of another
magnitude, order of magnitude
a number assigned to the ratio of two quantities; two quantities are of the same order of magnitude if one is less than 10 times as large as the other; the number of magnitudes that the quantities differ is specified to within a power of 10
output-to-input ratio
the output power of a transducer divided by the input power
prevalence
(epidemiology) the ratio (for a given time period) of the number of occurrences of a disease or event to the number of units at risk in the population
P/E ratio, price-to-earnings ratio
(stock market) the price of a stock divided by its earnings
productivity
(economics) the ratio of the quantity and quality of units produced to the labor per unit of time
proportionality
a ratio of two quantities that is constant
quotient
the ratio of two quantities to be divided
index of refraction, refractive index
the ratio of the velocity of light in a vacuum to that in a medium
relative humidity
the ratio of the amount of water in the air at a give temperature to the maximum amount it could hold at that temperature; expressed as a percentage
respiratory quotient
the ratio of the volume of carbon dioxide expired to the volume of oxygen consumed by an organism or cell in a given period of time
factor of safety, safety factor
the ratio of the breaking stress of a structure to the estimated maximum stress in ordinary use
S/N, signal-to-noise, signal-to-noise ratio, signal/noise, signal/noise ratio
the ratio of signal intensity to noise intensity
stoichiometry
(chemistry) the relation between the quantities of substances that take part in a reaction or form a compound (typically a ratio of whole integers)
time constant
the ratio of the inductance of a circuit in henries to its resistance in ohms
employee turnover, turnover, turnover rate
the ratio of the number of workers that had to be replaced in a given time period to the average number of workers
the ratio of the gross weight of an airplane to some factor determining its lift
eccentricity
(geometry) a ratio describing the shape of a conic section; the ratio of the distance between the foci to the length of the major axis
proportion
the quotient obtained when the magnitude of a part is divided by the magnitude of the whole
commensurateness, correspondence, proportionateness
the relation of corresponding in degree or size or amount
batting average, hitting average
(baseball) a measure of a batter's performance; the number of base hits divided by the number of official times at bat
fielding average
(baseball) a measure of a fielder's performance; the number of assists and putouts divided by the number of chances
figure of merit
a numerical expression representing the efficiency of a given system, material, or procedure
the average IQ of the adults in a given population
borderline intelligence
the minimal IQ required for someone to function normally and independently in the world (without some form of institutional assistance)
the ratio of the weight of an airplane to its engine power