/ Dictionary / Index A agnathan: Meaning and Definition of Find definitions for: ag•na•than Pronunciation: (ag'nu-thun), [key] — n. any member of the vertebrate class Agnatha. —adj. agnathous. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: agnathan (Thesaurus) Agnatha agnathous Related Content Daily Word Quiz: boorish Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language