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
And within that galaxy, not only will stars live-and-die, and not only will star-formation cease once all of the gas has been consumed, but gravitational interactions will eject most of those stellar corpses, as well as the planet remnants that orbit them.
—
Big Think, 20 Feb. 2026
To investigate the possibility of active supermassive black holes killing star formation in neighboring galaxies, the team set about studying one of the brightest quasars ever seen, J0100+2802.
—Robert Lea, Space.com, 20 Feb. 2026
SpaceBorn United plans to allow fertilization and blastocyst formation to occur for about twenty embryos at a time in a three-dimensional growth medium while the device is in space, after which the embryos will be frozen.
—Literary Hub, 20 Feb. 2026
Seoul, South Korea — The week before Close Your Eyes stepped onto the stage for their first-ever solo concert, the seven members moved in practiced formation across a basement rehearsal studio in Seoul’s Gangnam district.
—Rebecca Cairns, CNN Money, 19 Feb. 2026
See All Example Sentences for formation
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Big Think, 20 Feb. 2026
To investigate the possibility of active supermassive black holes killing star formation in neighboring galaxies, the team set about studying one of the brightest quasars ever seen, J0100+2802.
—Robert Lea, Space.com, 20 Feb. 2026
SpaceBorn United plans to allow fertilization and blastocyst formation to occur for about twenty embryos at a time in a three-dimensional growth medium while the device is in space, after which the embryos will be frozen.
—Literary Hub, 20 Feb. 2026
Seoul, South Korea — The week before Close Your Eyes stepped onto the stage for their first-ever solo concert, the seven members moved in practiced formation across a basement rehearsal studio in Seoul’s Gangnam district.
—Rebecca Cairns, CNN Money, 19 Feb. 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 22 Feb. 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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