/ Dictionary / Index S SSN: Meaning and Definition of Find definitions for: SSN Pronunciation: [key] Social Security number. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. SSM SSPE Related Content Daily Word Quiz: arboreal Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language