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

The view tapers off into infinity.

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 of infinity

• 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

In terms of pools, there’s both a freshwater sports pool and top floor infinity offering that, from the right angle, seems to be a continuation of the sea itself. —Jonnie Bayfield, Condé Nast Traveler, 22 Jan. 2026

The pool deck on Norwegian Aura will be 20% larger than the ones found on the Aqua and Luna and the largest in the NCL fleet, with more seating, an additional infinity hot tub, a larger LED entertainment screen and extra open lounge areas. —Patrick Connolly, The Orlando Sentinel, 15 Jan. 2026

To sidestep the inconvenience of infinity, mathematicians have recently focused their search on singularities with a special property called self-similarity. —Quanta Magazine, 9 Jan. 2026

Out back, a heated saline infinity-edge pool and spa looks out on the water in the near distance. —Tori Latham, Robb Report, 6 Jan. 2026

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