/ Dictionary / Index A acid radical: Meaning and Definition of Find definitions for: ac'id rad"ical Pronunciation: [key] — Chem. Chem. the remainder of an acid molecule after acidic hydrogen has been removed. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. acid precipitation acid rain Related Content Daily Word Quiz: bungled Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language