Noun

1. A number by which another (the multiplicand) is to be multiplied.

   In the expression 5 × 7, the "5" is a multiplier.

2. An adjective indicating the number of times something is to be multiplied.

   English multipliers include "double" and "triple".

3. A ratio used to estimate total economic effect for a variety of economic activities.
4. Any of several devices used to enhance a signal