formation

noun

for·​ma·​tion fȯr-ˈmā-shən 

1

: an act of giving form or shape to something or of taking form : development

the formation of the planets

2

: something that is formed

new word formations

a rock formation

3

: the manner in which a thing is formed : structure

the peculiar formation of the heart

4

: a major kind of plant growth (such as forest, grassland, or tundra) characteristic of a broad ecological region

5

a

: any igneous, sedimentary, or metamorphic rock represented as a unit

b

: any sedimentary bed or consecutive series of beds sufficiently homogeneous or distinctive to be a unit

6

: an arrangement of a body or group of persons or things in some prescribed manner or for a particular purpose

flying in formation

Synonyms of formation

• layout
• format

Examples of formation in a Sentence

The book explains the formation of the planets.

The soldiers were marching in formation.

The team ran on the field and lined up in a punt formation.

Recent Examples on the Web

Stable rules are needed to support capital formation, especially at the scale required by frontier AI development. — Paulo Carvão, Forbes.com, 2 Aug. 2026

However, the more problematic reps were when Igbinosun was in man coverage and tried to pick up his assignment on a shallow crossing route from one side of the formation to the other. — Joe Buscaglia, New York Times, 1 Aug. 2026

Along with discovering sulfur crystals, shiny meteorites and other unusual rock formations, Curiosity has made some of its biggest discoveries about ancient Mars, the space agency said. — Paloma Chavez, PEOPLE, 31 July 2026

The legislation led to the formation of local agencies that are responsible for halting chronic declines in groundwater levels, including by imposing pumping limits and fees. — Ian James, Los Angeles Times, 31 July 2026

Word History

First Known Use

15th century, in the meaning defined at sense 1

Phrases Containing formation

• back-formation
• break formation
• I formation
• punt formation
• reticular formation
• self-formation
• spread formation
• T formation

Rhymes for formation

• ablation
• aeration
• bination
• carnation
• cassation
• castration
• causation
• centration
• cessation
• cetacean
• chelation
• citation

Kids Definition

formation

noun

for·​ma·​tion fȯr-ˈmā-shən 

1

: a forming of something

2

: something formed

3

: the manner in which a thing is formed : structure, shape

4

: a bed of rocks or series of beds recognizable as a unit

5

: an arrangement or grouping of persons, ships, or airplanes

Medical Definition

formation

noun

for·​ma·​tion fȯr-ˈmā-shən 

1

: an act of giving form or shape to something or of taking form : development

2

: the manner in which a thing is formed : structure