a number by which another number (the multiplicand) is multiplied

an instrument or device for multiplying or intensifying some effect

a person or thing that multiplies, e.g. a key-operated machine or mechanism or circuit on a machine that multiplies figures and records the products

the ratio between the total increase in national income arising from the change in one of the components of aggregate demand, e.g. investment, government expenditure, or exports, and the change in that component