from the GNU version of the Collaborative International Dictionary of English
- adj. Having twenty-four leaves to a sheet.
- 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 so made; -- usually written 24mo, or 24°.
from The Century Dictionary and Cyclopedia
- Said of a section of twenty-four pages in a book, on a sheet, or in form of type. Usually called twenty-four-mo.
Sorry, no etymologies found.