/ Dictionary / Index C circular definition: Meaning and Definition of Find definitions for: cir'cular defini'tion Pronunciation: [key] — Logic. Logic. a definition in which the definiendum (the expression being defined) or a variant of it appears in the definiens (the expression that defines it). Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. circular circular dichroism Related Content Daily Word Quiz: arid Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language