'Twenty-fourmo' definitions:

Definition of 'Twenty-fourmo'

From: GCIDE

Twenty-fourmo \Twen`ty-four"mo\, a. Having twenty-four leaves to a sheet; as, a twenty-fourmo form, book, leaf, size, etc. -- n. A book composed of sheets, each of which is folded into twenty-four leaves; hence, indicating more or less definitely a size of book whose sheets are so folded; -- usually written 24mo, or 24[deg]. [1913 Webster]