Twenty-fourmo
Pronunciation : Twen`ty-four"mo
Part of Speech : a.
Definition : Defn: Having twenty-four leaves to a sheet; as, a twenty-fourmo form, book, leaf, size, etc. -- n.
Defn: 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?.
Source : Webster's Unabridged Dictionary, 1913