1. vigesimo-quarto - Noun
2. vigesimo-quarto - Adjective
Having twenty-four leaves to a sheet; as, a vigesimo-quarto form, book, leaf, size, etc.
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¡.
Source: Webster's dictionary