The Collaborative International Dictionary of English v.0.48:

Commutative \Com*mut"a*tive\, a. [CF. F. commutatif.]
   1. Relative to exchange; interchangeable; reciprocal. --
      Com*mut"a*tive"ly, adv.
      [1913 Webster]

            Rich traders, from their success, are presumed . . .
            to have cultivated an habitual regard to commutative
            justice.                              --Burke.
      [1913 Webster]

   2. (Math.) having the property of commutativity.
      [PJC]

WordNet (r) 3.0 (2006):

commutative
    adj 1: (of a binary operation) independent of order; as in e.g.
           "a x b = b x a"