/ Dictionary / Index R reserve capacity: Meaning and Definition of Find definitions for: reserve' capac"ity Pronunciation: [key] — Auto. Auto. the capacity of a battery, measured in minutes, to keep a vehicle operating if the charging system fails. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. reserve buoyancy reserve clause Related Content Daily Word Quiz: neologism Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language