2 Christian Church, historical a service book, especially one with the forms of service used at ordinations.
1relating to the order of something in a series:ordinal scales
relating to an ordinal number.
2 Biology relating to a taxonomic order.
Middle English(in ordinal (sense 2 of the noun)): the noun from medieval Latin ordinale (neuter); the adjective from late Latin ordinalis 'relating to order in a series', from Latin ordo, ordin-(see order)
ordinal in other Oxford dictionaries
Definition of ordinal in the US English dictionary