[twen-tee-fawr-moh, -fohr-, twuhn-] 
noun, plural -mos, adjective | 1. | a book size of about 3 5/8 × 5 1/8 in. (9 × 13 cm), determined by printing on sheets folded to form 24 leaves or 48 pages. |
| 2. | a book of this size. Symbol: 24mo, 24° |
| 3. | in twenty-fourmo. |
tiˈfɔr