/ Dictionary / Index F flat sour: Meaning and Definition of Find definitions for: flat' sour" Pronunciation: [key] fermentation occurring in canned foods after sealing. canned food so fermented. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. flat silver flatten Related Content Daily Word Quiz: soporific Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language