n. pl. thir·ty-two·mos
1. The page size (3.5 by 5.5 inches) that results when a printer's sheet is folded into 32 equal sections.
2. A book composed of pages of this size.
n, pl -mos
(Printing, Lithography & Bookbinding) a book size resulting from folding a sheet of paper into 32 leaves or 64 pages. Often written: 32mo or 32°