/ Dictionary / Index M mental reservation: Meaning and Definition of Find definitions for: men'tal reserva'tion Pronunciation: [key] an unexpressed doubt or qualification about a situation, person, etc. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. mentally mental retardation Related Content Daily Word Quiz: impetuous Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language