/ Dictionary / Index U underlet: Meaning and Definition of Find definitions for: un•der•let Pronunciation: (un"dur-let'), [key] — -let, -let•ting. to let below the true value. to sublet. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. underlayment underlie Related Content Daily Word Quiz: serendipity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language