/ Dictionary / Index U underpin: Meaning and Definition of Find definitions for: un•der•pin Pronunciation: (un"dur-pin'), [key] — -pinned, -pin•ning. to prop up or support from below; strengthen, as by reinforcing a foundation. to replace or strengthen the foundation of (a building or the like). to furnish a foundation for; corroborate: The author's conclusions are underpinned by references to experimental findings. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: underpin (Thesaurus) underperform underpinning 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