/ Dictionary / Index U upper bound: Meaning and Definition of Find definitions for: up'per bound' Pronunciation: [key] — Math. Math. an element greater than or equal to all the elements in a given set: 3 and 4 are upper bounds of the set consisting of 1, 2, and 3. Cf. (def. 4), Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. Upper Austria Upper Canada Related Content Daily Word Quiz: fidelity Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language