n. [ Prop., in sixteenth; fr. L. decimus tenth + sextus sixth. ] A book consisting of sheets, each of which is folded into sixteen leaves; hence, indicating, more or less definitely, a size of book; -- usually written 16mo or 16°. [ 1913 Webster ]

a. Having sixteen leaves to a sheet; as, a decimosexto form, book, leaf, size. [ 1913 Webster ]