noun, an arithmetical operation, defined initially in terms of repeated addition, usually written a ✕ b, a.b, or ab, by which the product of two quantities is calculated: to multiply a by positive integral b is to add a to itself b times. Multiplication by fractions can then be defined in the light of the associative and commutative properties; multiplication by 1/n is equivalent to multiplication by 1 followed by division by n: for example 0.3 ✕ 0.7 = 0.3 ✕ 7/10 = (0.3 ✕ 7)/10 = 2.1/10 = 0.21

From Collins

©HarperCollins 2008. Collins English Dictionary definition of multiplication