/ Dictionary / Index J jumbo: Meaning and Definition of Find definitions for: jum•bo Pronunciation: ( jum'bō), [key] — n., pl. adj. -bos, —n. a very large person, animal, or thing. See a forestaysail having a boom(jum&prim;bo boom&sec;)along its foot, used esp. on schooners. a sail used in place of a course on a square-rigged ship, having the form of an isosceles triangle set apex downward. a narrow triangular sail set point downward in place of a foresail on a topsail schooner. —adj. very large: the jumbo box of cereal. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: jumbo (Thesaurus) jumble sale jumbo jet Related Content Daily Word Quiz: fabricate Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language