/ Dictionary / Index B Bull Moose: Meaning and Definition of Find definitions for: Bull' Moose' Pronunciation: (m'sur). [key] a member of the Progressive Party under the leadership of Theodore Roosevelt. Also called Bull&prim; Moos&prim;er Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. bullmastiff bullneck Related Content Daily Word Quiz: procrastinate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language