/ Dictionary / Index M mostly: Meaning and Definition of Find definitions for: most•ly Pronunciation: (mōst'lē), [key] — adv. for the most part; in the main: The work is mostly done. chiefly; principally. generally; customarily. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: mostly (Thesaurus) most-favored-nation clause Most Reverend Related Content Daily Word Quiz: censure Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language