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
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
Iran has been a theocracy since 1979, when clerics toppled a secular monarch allied with the West, leading to the formation of the Islamic Republic led by Khamenei’s predecessor, Ayatollah Ruhollah Khomeini.
—
Mostafa Salem, CNN Money, 12 Jan. 2026
Jacobs gained no yards on two first-down runs during the possession (both were RPOs from shotgun formations, which limit options in the run game but can lighten the box to enable better rushing).
—Mike Sando, New York Times, 12 Jan. 2026
As such, the study of GoHam and the discovery of tantalizing hints of planet formation could give astronomers a better understanding of how giant planets form at great distances from their parent stars.
—Robert Lea, Space.com, 12 Jan. 2026
Mayer invited Weir for a performance, which led to the formation of Dead and Company.
—Denise Petski, Deadline, 12 Jan. 2026
See All Example Sentences for formation
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Mostafa Salem, CNN Money, 12 Jan. 2026
Jacobs gained no yards on two first-down runs during the possession (both were RPOs from shotgun formations, which limit options in the run game but can lighten the box to enable better rushing).
—Mike Sando, New York Times, 12 Jan. 2026
As such, the study of GoHam and the discovery of tantalizing hints of planet formation could give astronomers a better understanding of how giant planets form at great distances from their parent stars.
—Robert Lea, Space.com, 12 Jan. 2026
Mayer invited Weir for a performance, which led to the formation of Dead and Company.
—Denise Petski, Deadline, 12 Jan. 2026
See All Example Sentences for formation
Cite this Entry
“Formation.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/formation. Accessed 19 Jan. 2026.
Copy CitationKids Definition
formation
noun
for·ma·tion
fȯr-ˈmā-shən
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
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