/ Dictionary / Index U Upper Peninsula: Meaning and Definition of Find definitions for: Up'per Penin'sula Pronunciation: [key] the peninsula between lakes Superior and Michigan constituting the N part of Michigan. Abbr.: U.P. &hasp;Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. upper partial tone upper school Related Content Daily Word Quiz: endear Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language