Meaning of ordinal number

or'dinal num'ber

1. Also calledany of the numbers that express degree, quality, or position in a series, as first, second, and third (distinguished from cardinal number).
2. 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.