/ Dictionary / Index U underproof: Meaning and Definition of Find definitions for: un•der•proof Pronunciation: (un'dur-prf'), [key] — adj. containing a smaller proportion of alcohol than proof spirit. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. underproduction underprop Related Content Daily Word Quiz: pugilist Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language