or·di·nal 
(ôrdn-əl)
(ôrdn-əl)adj.
1. Being of a specified position in a numbered series: an ordinal rank of seventh.
2. Of or relating to a taxonomic order.
n.
1. An ordinal number.
2. Ecclesiastical
a. A book of instructions for daily services.
b. A book of forms for ordination.
[Middle English ordinel, orderly, regular, from Late Latin ōrdinālis, ordinal, from Latin ōrdō, ōrdin-, order; see ar- in the Appendix of Indo-European roots. N., sense 2, from Middle English, from Medieval Latin ōrdināle, from Late Latin, neuter sing. of ōrdinālis, ordinal.]