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. (Science: mathematics) That number placed below the line in vulgar fractions which shows into how many parts the integer or unit is divided.
thus, in 3/5, 5 is the denominator, showing that the integer is divided into five parts; and the numerator, 3, shows how many parts are taken.
3. (Science: mathematics) That part of any expression under a fractional form which is situated below the horizontal line signifying division.
in this sense, the denominator is not necessarily a number, but may be any expression, either positive or negative, real or imaginary.
Origin: cf. F. Denominateur.