1. Being of a specified position in a numbered series: an ordinal rank of seventh.
2. Of or relating to a taxonomic order.
1. An ordinal number.
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.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.