/ Dictionary / Index T twelfth: Meaning and Definition of Find definitions for: twelfth Pronunciation: (twelfth), [key] — adj. next after the eleventh; being the ordinal number for 12. being one of 12 equal parts. —n. a twelfth part, esp. of one (). the twelfth member of a series. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: twelfth (Thesaurus) tweezers Twelfth Amendment Related Content Daily Word Quiz: panacea Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language