forty-eightmo

US: (fôr′tē āt′mō)

WordReference Random House Unabridged Dictionary of American English © 2025

for•ty-eight•mo  (fôr′tē āt′mō), n., pl. -mos for 2, adj. 
n. 

1. Printing a book size of about 2½ × 4 in. (6 × 10 cm), determined by printing on sheets folded to form 48 leaves or 96 pages. Abbr.: 48mo, 48°
2. Printing a book of this size.

adj. 

3. Printing in forty-eightmo.

• forty-eight + -mo 1885–90