firmament

American  

[fur-muh-muhnt] / ˈfɜr mə mənt /

noun

1. the vault of heaven; sky.

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firmament British  

/ ˈfɜːməmənt, ˌfɜːməˈmɛntəl /

noun

1. the expanse of the sky; heavens

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Other Word Forms

• firmamental
  adjective

Etymology

Origin of firmament

1250–1300; Middle English < Late Latin firmāmentum sky, Latin: support, prop, stay, equivalent to firmā ( re ) to strengthen, support ( see firm ²) + -mentum -ment

Explanation

The firmament is the curve of the sky, especially if you imagine it as a solid surface. You can describe the sky at night as a firmament shining with stars (if you're feeling poetic). The word firmament comes from the Latin firmus, or "firm," and this description of the sky as something solid reflects ancient ideas of the way the universe was constructed. The first stargazers imagined the sky as a sphere, and it wasn't until the late 1500s that the idea of an infinite universe was seriously considered. Today the word firmament is mostly literary, used to poetically describe the visual curve of the sky.

Example Sentences

See Examples For:

firmament

It is our fervent belief that this conversation about the role of the court in the U.S. legal firmament will serve to make the court more durable.

From Slate ● Jul. 20, 2026

Announcing his campaign before she officially made that decision — or had the chance to choose her successor — sent shock waves through the political firmament.

From Los Angeles Times ● Jun. 8, 2026

Taix’s history, and its spot in the city’s cultural firmament, cannot be denied.

From Los Angeles Times ● Mar. 26, 2026

Still, his place in the basketball firmament was long since secured.

From The Wall Street Journal ● Nov. 23, 2025

He made motions like tying strings into bundles, then tacked them to the firmament above him in the same way garlands were hung at the festivals in Mologa.

From Anya and the Dragon by Sofiya Pasternack