A formation is an arrangement of people or things. Planes flying in formation make a deliberate, specific pattern in the sky.

Some formations are on purpose, or deliberate — like military troops marching in formation or a cheerleading squad arranging itself in formation. Others just arrange themselves in a particular way by chance, like a striking cloud formation overhead. You can also talk about the formation — or establishment — of something less physical, like the formation of a new government. The Latin root, formationem, means "a shaping."

Definitions of formation
  1. noun
    the act of forming or establishing something
    synonyms: constitution, establishment, organisation, organization
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    unionisation, unionization
    act of forming labor unions
    collectivisation, collectivization
    the organization of a nation or economy on the basis of collectivism
    communisation, communization
    the organization of a nation of the basis of communism
    the act of constituting a political unity out of a number of separate states or colonies or provinces so that each member retains the management of its internal affairs
    colonisation, colonization, settlement
    the act of colonizing; the establishment of colonies
    the act or process of establishing a city or organization as a legal entity
    the act of populating (causing to live in a place)
    type of:
    beginning, commencement, start
    the act of starting something
  2. noun
    natural process that causes something to form
    “the formation of gas in the intestine”
    “the formation of crystals”
    “the formation of pseudopods”
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    encrustation, incrustation
    the formation of a crust
    (photography) the formation of a network of cracks or wrinkles in a photographic emulsion
    type of:
    action, activity, natural action, natural process
    a process existing in or produced by nature (rather than by the intent of human beings)
  3. noun
    the act of fabricating something in a particular shape
    synonyms: shaping
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    the act of using a file (as in shaping or smoothing an object)
    shaping metal by heating and hammering
    metalwork, metalworking
    the activity of making things out of metal in a skillful manner
    the act of forming something into granules or grains
    grooving, rifling
    the cutting of spiral grooves on the inside of the barrel of a firearm
    the activity of shaping something on a lathe
    type of:
    fabrication, manufacture, manufacturing
    the act of making something (a product) from raw materials
  4. noun
    creation by mental activity
    “the formation of sentences”
    “the formation of memories”
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    formation of a word by means of an affix
    formation of a word by means of a prefix
    formation of a word by means of a suffix
    type of:
    creating by mental acts
    the act of creating something by thinking
  5. noun
    a particular spatial arrangement
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    the rectangular formation of parallel scanning lines that guide the electron beam on a television screen or a computer monitor
    rig, rigging
    formation of masts, spars, sails, etc., on a vessel
    (tenpin bowling) a divided formation of pins left standing after the first bowl
    Bermuda rig, Bermudan rig, Bermudian rig, Marconi rig
    a rig of triangular sails for a yacht
    cat rig
    rig of a catboat
    fore-and-aft rig
    rig in which the principal sails are fore-and-aft
    the rig on a lateen-rigged sailing vessel
    type of:
    arrangement, placement
    the spatial property of the way in which something is placed
  6. noun
    an arrangement of people or things acting as a unit
    “a defensive formation
    “a formation of planes”
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    a formation of aircraft in flight
    military formation
    a formation of troops
    the offensive football players who line up behind the linemen
    the defensive football players who line up behind the linemen
    a formation of people or things one behind another
    a formation of people or things one beside another
    the middle of a military or naval formation
    flank, wing
    the side of military or naval formation
    the front of a military formation or procession
    the back of a military formation or procession
    rivet line
    a line of rivets at a seam
    chorus, chorus line
    a body of dancers or singers who perform together
    an oblique line of squares of the same color on a checkerboard
    open order
    a military formation leaving enough space between ranks to allow an inspecting officer to pass
    close order
    a military formation for drill or marching
    extended order
    a military formation for skirmishing; as widely separated as the tactical situation permits
    sick call, sick parade
    the daily military formation at which individuals report to the medical officer as sick
    Indian file, file, single file
    a line of persons or things ranged one behind the other
    the football players who line up on the line of scrimmage
    line of march
    the arrangement of people in a line for marching
    line of succession
    the order in which individuals are expected to succeed one another in some official position
    a line of persons arranged by police for inspection or identification
    picket line
    a line of people acting as pickets
    an arrangement of objects or people side by side in a line
    a row or line of people (especially soldiers or police) standing abreast of one another
    conga line
    a line of people in single file performing the conga dance
    trap line
    a line or series of traps
    queue, waiting line
    a line of people or vehicles waiting for something
    type of:
    an orderly grouping (of things or persons) considered as a unit; the result of arranging
  7. noun
    (geology) the geological features of the earth
    synonyms: geological formation
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    Pillars of Hercules
    the two promontories at the eastern end of the Strait of Gibraltar; according to legend they were formed by Hercules
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    underground bed or layer yielding groundwater for wells, springs, etc.
    an area of sand sloping down to the water of a sea or lake
    a geological formation consisting of an underground enclosure with access from the surface of the ground or from the sea
    cliff, drop, drop-off
    a steep high face of rock
    a low area of alluvial deposits where a river divides before entering a larger body of water
    a domed rock formation where a core of rock has moved upward and pierced through the more brittle overlying strata
    a thin layer or stratum of (especially metamorphic) rock
    the part of the seashore between the highwater mark and the low-water mark
    ice mass
    a large mass of ice
    land bordering a lake
    a block of the earth's crust bounded by faults and shifted to form peaks of a mountain range
    a geological formation in which all strata are inclined in the same direction
    the point where a stream issues into a larger body of water
    depression, natural depression
    a sunken or depressed geological formation
    elevation, eminence, natural elevation
    a raised or elevated geological formation
    land bordering an ocean
    chain, chain of mountains, mountain chain, mountain range, range, range of mountains
    a series of hills or mountains
    geological feature that is a remnant of a pre-existing formation after other parts have disappeared
    ridge, ridgeline
    a long narrow range of hills
    a long narrow natural elevation on the floor of the ocean
    the land along the edge of a body of water
    incline, side, slope
    an elevated geological formation
    fountain, natural spring, outflow, outpouring, spring
    a natural flow of ground water
    scree, talus
    a sloping mass of loose rocks at the base of a cliff
    mineral vein, vein
    a layer of ore between layers of rock
    crater, volcanic crater
    a bowl-shaped geological formation at the top of a volcano
    a vertical (or almost vertical) smooth rock face (as of a cave or mountain)
    groundwater level, water level, water table
    underground surface below which the ground is wholly saturated with water
    a sharp narrow ridge found in rugged mountains
    acclivity, ascent, climb, raise, rise, upgrade
    an upward slope or grade (as in a road)
    sloping land (especially the slope beside a body of water)
    bank, camber, cant
    a slope in the turn of a road or track; the outside is higher than the inside in order to reduce the effects of centrifugal force
    a natural depression in the surface of the land often with a lake at the bottom of it
    bed, bottom
    a depression forming the ground under a body of water
    an especially rich vein of precious ore
    a large crater caused by the violent explosion of a volcano that collapses into a depression
    the steeply sloping side of a canyon
    a large cave or a large chamber in a cave
    a slope down which sleds may coast
    small or narrow cave in the side of a cliff or mountain
    a steep rugged rock or cliff
    a bowl-shaped depression formed by the impact of a meteorite or bomb
    declension, declination, decline, declivity, descent, downslope, fall
    a downward slope or bend
    escarpment, scarp
    a long steep slope or cliff at the edge of a plateau or ridge; usually formed by erosion
    Fountain of Youth
    a fountain described in folk tales as able to make people young again
    a spring that discharges hot water and steam
    a slowly moving mass of ice
    grot, grotto
    a small cave (usually with attractive features)
    highland, upland
    elevated (e.g., mountainous) land
    a local and well-defined elevation of the land
    the side or slope of a hill
    hogback, horseback
    a narrow ridge of hills
    hole, hollow
    a depression hollowed out of solid matter
    hot spring, thermal spring
    a natural spring of water at a temperature of 70 F or above
    berg, iceberg
    a large mass of ice floating at sea; usually broken off of a polar glacier
    ice cap, icecap
    a mass of ice and snow that permanently covers a large area of land (e.g., the polar regions or a mountain peak)
    ice field
    a large flat mass of ice (larger than an ice floe) floating at sea
    floe, ice floe
    a flat mass of ice (smaller than an ice field) floating at sea
    lakeshore, lakeside
    the shore of a lake
    low level country
    a flat-bottomed volcanic crater that was formed by an explosion; often filled with water
    mount, mountain
    a land mass that projects well above its surroundings; higher than a hill
    mountainside, versant
    the side or slope of a mountain
    a gentle slope leading from the base of a mountain to a region of flat land
    the beach at a seaside resort
    a very steep cliff
    foreland, head, headland, promontory
    a natural elevation (especially a rocky one that juts out into the sea)
    a long narrow natural elevation or striation
    coast, sea-coast, seacoast, seashore
    the shore of a sea or ocean
    sink, sinkhole, swallow hole
    a depression in the ground communicating with a subterranean passage (especially in limestone) and formed by solution or by collapse of a cavern roof
    ski slope
    a snow-covered slope for skiing
    a poetic term for a shore (as the area periodically covered and uncovered by the tides)
    a rounded elevation (especially one on an ocean floor)
    deep, oceanic abyss, trench
    a long steep-sided depression in the ocean floor
    a narrow depression (as in the earth or between ocean waves or in the ocean bed)
    vale, valley
    a long depression in the surface of the land that usually contains a river
    type of:
    object, physical object
    a tangible and visible entity; an entity that can cast a shadow
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