/ Dictionary / Index B BCS theory: Meaning and Definition of Find definitions for: BCS theory Pronunciation: [key] a general quantum theory of superconductivity that describes many properties of superconducting materials. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. BC soil BD. Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language