/ Dictionary / Index A Agnatha: Meaning and Definition of Find definitions for: Ag•na•tha Pronunciation: (ag'nu-thu), [key] — n. the class of vertebrates comprising the lampreys, hagfishes, and several extinct forms, having no jaws or paired appendages. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: agnatha (Thesaurus) agnate agnathan Related Content Daily Word Quiz: eccentric Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language