/ Dictionary / Index E eightieth: Meaning and Definition of Find definitions for: eight•i•eth Pronunciation: (ā'tē-ith), [key] — adj. next after the seventy-ninth; being the ordinal number for 80. being one of 80 equal parts. —n. an eightieth part, esp. of one (). the eightieth member of a series. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: eightieth (Thesaurus) eight-hundred number eightpenny Related Content Daily Word Quiz: secular Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language