De*nom"i*na`tor (?), *n.* [Cf. F.
*dénominateur*.] **1.** One who, or that
which, gives a name; origin or source of a name.

This opinion that Aram . . . was the father and
*denomination* of the Syrians in general.

*Sir W.
Raleigh.***2.** *(Arith.)* That number placed below
the line in vulgar fractions which shows into how many parts the
integer or unit is divided.

&fist; Thus, in ⅗, 5 is the *denominator*, showing
that the integer is divided into five parts; and the numerator, 3,
shows how many parts are taken.

**3.** *(Alg.)* That part of any expression
under a fractional form which is situated below the horizontal line
signifying division.

&fist; In this sense, the *denominator* is not necessarily a
number, but may be any expression, either positive or negative, real
or imaginary. *Davies & Peck (Math. Dict. )*