ordinal number

noun

Also called ordinal numeral. any of the numbers that express degree, quality, or position in a series, as first, second, and third (distinguished from cardinal number).

Mathematics. a symbol denoting both the cardinal number and the ordering of a given set, being identical for two ordered sets having elements that can be placed into one-to-one correspondence, the correspondence preserving the order of the elements.

Origin of ordinal number

First recorded in 1600–10

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

British Dictionary definitions for ordinal numbers

ordinal number

noun

a number denoting relative position in a sequence, such as first, second, thirdSometimes shortened to: ordinal

logic maths a measure of not only the size of a set but also the order of its elements

Compare cardinal number

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

ordinal numbers in Science

ordinal number

[ôr′dn-əl]

A number, such as 3rd, 11th, or 412th, used in counting to indicate position in a series but not quantity. Compare cardinal number.

ordinal numbers in Culture

ordinal numbers

Numbers that indicate the order or position of something in a group or set, such as first, second, or fifteenth. (Compare cardinal numbers.)