/ Dictionary / Index F forty-eightmo: Meaning and Definition of Find definitions for: for•ty-eight•mo Pronunciation: (fôr'tē āt'mō), [key] — n., pl. adj. -mos —n. a book size of about 2 × 4 in. (6 × 10 cm), determined by printing on sheets folded to form 48 leaves or 96 pages. Abbr.: 48mo, 48° a book of this size. —adj. in forty-eightmo. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. forty-eighth forty-fifth Related Content Daily Word Quiz: gregarious Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language