/ Dictionary / Index U unthankful: Meaning and Definition of Find definitions for: un•thank•ful Pronunciation: (un-thangk'ful), [key] — adj. not thankful; ungrateful. not repaid with thanks; thankless: an unthankful task. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: unthankful (Thesaurus) untether unthatch Related Content Daily Word Quiz: spectral Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language