| 1. | 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 ). |
| 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. |
| ordinal number n. A number indicating position in a series or order. The ordinal numbers are first (1st), second (2nd), third (3rd), and so on. |
ordinal number  (ôr'dn-əl) Pronunciation Key
A number, such as 3rd, 11th, or 412th, used in counting to indicate position in a series but not quantity. Compare cardinal number. |