/ Dictionary / Index S sesquicentennial: Meaning and Definition of Find definitions for: ses•qui•cen•ten•ni•al Pronunciation: (ses"kwi-sen-ten'?-ul), [key] ? adj. pertaining to or marking the completion of a period of 150 years. ?n. a 150th anniversary or its celebration. Random House Unabridged Dictionary, Copyright 1997, by Random House, Inc., on Infoplease. See also: sesquicentennial (Thesaurus) sesquicarbonate sesquioxide Related Content Daily Word Quiz: sumptuous Analogy of the Day: Today?s Analogy Spelling Bee: Today?s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language