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.

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

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

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