twentymo

[ twen-tee-moh, twuhn- ]

noun

, plural twen·ty·mos.

1. a book size of about 3 × 5 inches (8 × 12 centimeters), determined by printing on sheets folded to form 20 leaves or 40 pages.
2. a book of this size. : 20mo, 20°

adjective

1. in twentymo.

Word History and Origins

Origin of twentymo¹

First recorded in 1835–45; twenty + -mo