Denominator

Part of speech: noun (n.)

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. That number placed below the line in vulgar fractions which shows into how many parts the integer or unit is divided.

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