/ Dictionary / Index S so long: Meaning and Definition of Find definitions for: so" long' Pronunciation: [key] — Informal. Informal. good-bye: I said so long and left. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Solon Solothurn Related Content Daily Word Quiz: sinister Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language