Fac"tor (?), n. [L. factor a doer: cf. F. facteur a factor. See Fact.] 1. (Law) One who transacts business for another; an agent; a substitute; especially, a mercantile agent who buys and sells goods and transacts business for others in commission; a commission merchant or consignee. He may be a home factor or a foreign factor. He may buy and sell in his own name, and he is intrusted with the possession and control of the goods; and in these respects he differs from a broker. Story. Wharton.

My factor sends me word, a merchant's fled
That owes me for a hundred tun of wine.

2. A steward or bailiff of an estate. [Scot.] Sir W. Scott.

3. (Math.) One of the elements or quantities which, when multiplied together, form a product.

4. One of the elements, circumstances, or influences which contribute to produce a result; a constituent.

The materal and dynamical factors of nutrition.
H. Spencer.

Fac"tor, v. t. [imp. & p. p. Factored (-t?rd); p. pr. & vb. n. Factoring.] (Mach.) To resolve (a quantity) into its factors.