ordinal number

WordReference Random House Learner's Dictionary of American English © 2026

ˈor•di•nal ˈnum•ber, n. [countable]

1. Mathematics a number that expresses position in a series, as first, second, or third.

WordReference Random House Unabridged Dictionary of American English © 2026

or′dinal num′ber, 

1. Mathematics Also called or′dinal nu′meral. any of the numbers that express degree, quality, or position in a series, as first, second, and third (distinguished from cardinal number).
2. 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.
• 1600–10

Collins Concise English Dictionary © HarperCollins Publishers::

ordinal number noun

1. a number denoting relative position in a sequence, such as first, second, third
   Sometimes shortened to: ordinal

Compare cardinal number