infinity

noun

in·​fin·​i·​ty in-ˈfi-nə-tē 

plural infinities

1

a

: the quality of being infinite

b

: unlimited extent of time, space, or quantity : boundlessness

2

: an indefinitely great number or amount

an infinity of stars

3

a

: the limit of the value of a function or variable when it tends to become numerically larger than any preassigned finite number

b

: a part of a geometric magnitude that lies beyond any part whose distance from a given reference position is finite

do parallel lines ever meet if they extend to infinity

c

: a transfinite number (such as aleph-null)

4

: a distance so great that the rays of light from a point source at that distance may be regarded as parallel

Synonyms

• perpetuity
• eternity

Examples of infinity in a Sentence

The view tapers off into infinity.

a series of numbers that continues to infinity

The night sky was filled with an infinity of stars.

Recent Examples on the Web

No, the symbol for infinity replaces the 11. —Marco Della Cava, USA Today, 8 Sep. 2025

Conrad also says goodbye to Belly and returns the infinity necklace to her. —Dina Kaur, AZCentral.com, 3 Sep. 2025

At zero velocity, γ equals one, while as velocity gets close to the speed of light, γ approaches infinity. —Don Lincoln, Big Think, 29 Aug. 2025

For those who love swimming, there is also an infinity-edge 80-foot pool. —Giulia Carbonaro, MSNBC Newsweek, 26 Aug. 2025

Word History

Etymology

Middle English infinite, borrowed from Anglo-French infinité, borrowed from Latin infīnitāt-, infīnitās, from in- in- entry 1 + fīnis "boundary, limit, terminal point, ending" + -itāt-, -itās -ity — more at final entry 1

First Known Use

14th century, in the meaning defined at sense 1a

Phrases Containing infinity

• infinity pool
• infinity scarf

Rhymes for infinity

• affinity
• divinity
• salinity
• vicinity
• virginity
• alkalinity
• consanguinity
• crystallinity
• femininity
• masculinity

Kids Definition

infinity

noun

in·​fin·​i·​ty in-ˈfin-ət-ē 

plural infinities

1

a

: the quality of being infinite

b

: a space, quantity, or period of time that is without limit

2

: an indefinitely great number or amount

3

: a point infinitely far away

Etymology

Middle English infinite "the quality of having no limit," from early French infinité (same meaning), derived from Latin infinitus (adjective) "having no limit," from in- "not" and finitus, past participle of finire "to limit, bring to an end," from finis "end, limit" — related to define, final, finish