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

Poway’s Kumeyaay-Ipai Interpretive Center is considered a sacred site in part because the rock formations around it resemble animals. —Julie Gallant, San Diego Union-Tribune, 23 Jan. 2026

The University of Washington product has seen his role grow as the Patriots have leaned more heavily into jumbo formations and their rushing attack. —Doug Kyed, Boston Herald, 23 Jan. 2026

Granite boulders and undulating rock formations surrounded by namesake Joshua trees (Yucca brevifolia) majestically reside among nearly 800 species of plants, from annually blooming wildflowers, to hardy bushes and palms, to 15 types of colorful and peculiar cacti. —Condé Nast, Condé Nast Traveler, 23 Jan. 2026

Zach Charbonnet is done but Seattle should be able rely on the other side of its two-headed in Kenneth Walker III and control the clock from its two-tight end formations. —Hank Gola, New York Daily News, 23 Jan. 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
• bination
• carnation
• cassation
• castration
• causation
• centration
• cessation
• cetacean
• chelation
• citation
• collation

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