/ Dictionary / Index M medium quarto: Meaning and Definition of Find definitions for: me'dium quar'to Pronunciation: [key] a size of book, about 9 × 12 in. (24 × 30 cm), untrimmed. Abbr.: medium 4to Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. medium of exchange medium-scale integration Related Content Daily Word Quiz: exemplary Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language