/ Dictionary / Index T twenty-fourmo: Meaning and Definition of Find definitions for: twen•ty-four•mo Pronunciation: (twen"tē-fôr'mō, -fōr'-, twun'-), [key] — n., pl. adj. -mos, —n. a book size of about 3 × 5 in. (9 × 13 cm), determined by printing on sheets folded to form 24 leaves or 48 pages. a book of this size. Symbol: 24mo, 24° —adj. in twenty-fourmo. Also called Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. twenty-four twenty-fourth Related Content Daily Word Quiz: winsome Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language