Multiply

From Old French multiplier, from Latin multiplicÅ, from multi ("many") + plicÅ ("I fold").

The noun presumably derives from the verb.

Full definition of multiply

(transitive, arithmetic) To perform multiplication on (a number).
when you multiply 3 by 7, you get 21; he multiplied several numbers
(intransitive) To grow in number.
(intransitive) To breed or propagate.

2013-07-20, Welcome to the plastisphere, researchers noticed many of their pieces of marine debris sported surface pits around two microns across....Closer examination showed that some of these pits did, indeed, contain bacteria, and that in several cases these bacteria were dividing and thus, by the perverse arithmetic of biological terminology, multiplying.

(intransitive, arithmetic) To perform multiplication.
He had been multiplying, but it occurred to him he needed to resolve the exponents, first.
(transitive, rare) To be a factor in a multiplication with (another factor).

1983, Graham Flegg, Numbers, 2002 Dover Publications edition, ISBN 0486421651, page 154 http://books.google.com/books?id=C0Wcb9c6c18C&pg=PA154&dq=multiplies:This follows a similar process, counters having to be removed and replaced at each stage of the remaining part of the calculation except the final one, where 2 multiplies 3 to give 6.
1993, Edward T. Dowling, Schaum's Outline of Theory and Problems of Mathematical Methods for Business and Economics, ISBN 0070176744, page 14 http://books.google.com/books?id=8PaQk7LodfoC&pg=PA14&dq=multiplies:Of all the possible combinations of factors above, only $(2\cdot4)+(3\cdot5)=23$ . Carefully arranging the factors, therefore, to ensure that 2 multiplies 4 and 3 multiplies 5, we have
6x^2+23x+20=(2x+5)(3x+4)

(plural multiplies)