cardinal number


Also called cardinal numeral. any of the numbers that express amount, as one, two, three, etc. (distinguished from ordinal number).
Also called potency, power. Mathematics. a number or symbol analogous to the number of elements in a finite set, being identical for two sets that can be placed into one-to-one correspondence: The cardinal number of the set a1, a2, … an is n.

Nearby words

  1. cardinal,
  2. cardinal beetle,
  3. cardinal flower,
  4. cardinal grosbeak,
  5. cardinal ligament,
  6. cardinal numbers,
  7. cardinal point,
  8. cardinal points,
  9. cardinal sign,
  10. cardinal sin

Origin of cardinal number

First recorded in 1585–95 Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for cardinal number

cardinal number

cardinal numeral


a number denoting quantity but not order in a setSometimes shortened to: cardinal
maths logic
  1. a measure of the size of a set that does not take account of the order of its membersCompare natural number
  2. a particular number having this function

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 cardinal number

cardinal number


1590s, "one, two, three," etc. as opposed to ordinal numbers "first, second, third," etc.; so called because they are the principal numbers and the ordinals depend on them (see cardinal (adj.)).

Online Etymology Dictionary, © 2010 Douglas Harper

Science definitions for cardinal number

cardinal number


A number, such as 3, 11, or 412, used in counting to indicate quantity but not order. Compare ordinal number.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.