/ Dictionary / Index U uncertainty: Meaning and Definition of Find definitions for: un•cer•tain•ty Pronunciation: (un-sûr'tn-tē), [key] — pl. -ties the state of being uncertain; doubt; hesitancy: His uncertainty gave impetus to his inquiry. an instance of uncertainty, doubt, etc. unpredictability; indeterminacy; indefiniteness. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: uncertainty (Thesaurus) uncertain uncertainty principle Related Content Daily Word Quiz: rustic Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language