1.  A cause or reason that contributes to some result.

2.  An agent hired to sell property on behalf of its owner.  The factor is given control and possession of the property from the start of the sale period until either the time of sale or the end of the agency relationship.

3.  Someone who buys accounts receivable in exchange for a lump sum of money.  The factor acquires rights to the future income stream from the accounts receivable, and the seller acquires immediate cash to fuel its business.