Number
in grammar, that distinctive form given to a word according as it is intended to express or is spoken of one individual or several individuals. In English there are two numbers: the singular, which denotes one, or a single individual; the plural, which is used when two or more individuals are spoken of.
In Greek, Sanskrit, and a few other languages, a third number was used, called the dual, when only two individuals are spoken of. In the oldest English a dual number existed in the case of pronouns.
In phrenology, the name given by Combe to one of the perceptive faculties, the seat of which is placed by Spurzheim just above the external angle of each eye.
It is supposed to give facility in arithmetical operations, and is called the organ of calculation.