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

Xabi Alonso might have been more interested than most to see Chelsea’s starting formation in the FA Cup final on Saturday. —Liam Twomey, New York Times, 17 May 2026

Al-Mainuki was born in 1982 in Mainok, or Mainuki, a village in Nigeria’s northeastern Borno, the heart of an insurgency crisis following the formation of the Boko Haram militant group around 2009. —ABC News, 16 May 2026

Note the two identical charts below, one with annotations depicting the bottoming out process underway, and one with the 150-day moving average, also depicting a bottoming out reversal formation. —Carter Braxton Worth, CNBC, 15 May 2026

The coupling that El Niño spawns between the atmosphere and the warmer water along the Equator tends to create sinking winds over the Atlantic that disrupt cloud formations that could otherwise become hurricanes. —Dinah Voyles Pulver, USA Today, 15 May 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