/ ˈɔːdɪnl; NAmE ˈɔːrdənl/ (also ˌordinal ˈnumber ) noun
a number that refers to the position of sth in a series, for example 'first', 'second', etc.
—compare cardinal
► or·din·al adjective
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WORD ORIGIN
Middle English (referring to a service book in the Christian church): the noun from medieval Latin ordinale (neuter); the adjective from late Latin ordinalis relating to order in a series, from Latin ordo , ordin- row, series, rank.