| 1. | Arithmetic. that term of a fraction, usually written under the line, that indicates the number of equal parts into which the unit is divided; divisor. Compare numerator (def. 1). |
| 2. | something shared or held in common; standard. |
| 3. | Archaic. a person or thing that denominates. |
In mathematics, the number that appears on the bottom of a fraction. In the fraction 2/3, the denominator is 3. (Compare numerator.)