/ Dictionary / Index S sign-on: Meaning and Definition of Find definitions for: sign-on Pronunciation: (sīn'on", -ôn"), [key] — n. the opening salutation, station identification, etc., at the beginning of the broadcast day. an act or instance of signing on. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: sign-on (Thesaurus) sign of the zodiac signor Related Content Daily Word Quiz: bungled Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language