/ Dictionary / Index S stepsister: Meaning and Definition of Find definitions for: step•sis•ter Pronunciation: (step'sis"tur), [key] — n. one's stepfather's or stepmother's daughter by a previous marriage. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: stepsister (Thesaurus) step rocket stepson Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language