noun, plural in·fin·i·ties.

Origin of infinity

1350–1400; Middle English infinite < Latin infīnitās, equivalent to in- in-3 + fīni(s) boundary (see finish) + -tās -ty2
Can be confusedaffinity infinity Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

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British Dictionary definitions for infinity


noun plural -ties

the state or quality of being infinite
endless time, space, or quantity
an infinitely or indefinitely great number or amount
optics photog a point that is far enough away from a lens, mirror, etc, for the light emitted by it to fall in parallel rays on the surface of the lens, etc
physics a dimension or quantity of sufficient size to be unaffected by finite variations
maths the concept of a value greater than any finite numerical value
a distant ideal point at which two parallel lines are assumed to meet
Symbol (for senses 4–7):
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for infinity

late 14c., from Old French infinité "infinity; large number or quantity" (13c.), from Latin infinitatem (nominative infinitas) "boundlessness, endlessness," from infinitus boundless, unlimited" (see infinite). Infinitas was used as a loan-translation of Greek apeiria "infinity," from apeiros "endless."

Online Etymology Dictionary, © 2010 Douglas Harper

infinity in Science



A space, extent of time, or quantity that has no limit.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.