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

And in infinity, Achilles catches the turtle. —Big Think, 25 Nov. 2025

The holiday event features more than 15 million lights and LED displays as well as infinity mirror rooms, interactive exhibits, circus performances, carnival games and an ice skating rink, The Sacramento Bee previously reported. —Don Sweeney, Sacbee.com, 24 Nov. 2025

Tim Allen has gone to infinity and beyond once again to bring fans another outing as Buzz Lightyear in Toy Story 5. —Glenn Garner, Deadline, 24 Nov. 2025

At the time, mathematicians were deeply uncomfortable with this menagerie of different infinities. —Joseph Howlett, Quanta Magazine, 21 Nov. 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