/ Dictionary / Index L law of contradiction: Meaning and Definition of Find definitions for: law' of contradic'tion Pronunciation: [key] — Logic. Logic. the law that a proposition cannot be both true and false or that a thing cannot both have and not have a given property. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. law of conservation of mass law of cosines Related Content Daily Word Quiz: denizen Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language