/ Dictionary / Index L Lewis base: Meaning and Definition of Find definitions for: Lew'is base' Pronunciation: [key] — Chem. Chem. any substance capable of forming a covalent bond with an acid by transferring a pair of electrons to it. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Lewis and Harris lewis bolt Related Content Daily Word Quiz: penchant Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language