/ Dictionary / Index P probably: Meaning and Definition of Find definitions for: prob•a•bly Pronunciation: (prob'u-blē), [key] — adv. in all likelihood; very likely: He will probably attend. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: probably (Thesaurus) probable error proband Related Content Daily Word Quiz: opulent Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language