Twenty-fourmo

1. 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?.
2. a. Having twenty-four leaves to a sheet; as, a twenty-fourmo form, book, leaf, size, etc.

The word meanings were obtained from OPTED(The Online Plain Text English Dictionary), which is based on “The Project Gutenberg Etext of Webster’s Unabridged Dictionary” which is in turn based on the 1913 US Webster’s Unabridged Dictionary (See Project Gutenburg), as a text file.