The Collaborative International Dictionary of English v.0.48:

Convolution \Con`vo*lu"tion\, n.
   1. The act of rolling anything upon itself, or one thing upon
      another; a winding motion.
      [1913 Webster]

            O'er the calm sea, in convolution swift,
            The feathered eddy floats.            --Thomson.
      [1913 Webster]

   2. The state of being rolled upon itself, or rolled or
      doubled together; a tortuous or sinuous winding or fold,
      as of something rolled or folded upon itself. --Blackmore.
      [1913 Webster]

   3. (Anat.) An irregular, tortuous folding of an organ or
      part; as, the convolutions of the intestines; the cerebral
      convolutions. See Brain.
      [1913 Webster]

WordNet (r) 3.0 (2006):

convolution
    n 1: the shape of something rotating rapidly [syn: whirl,
         swirl, vortex, convolution]
    2: a convex fold or elevation in the surface of the brain [syn:
       gyrus, convolution]
    3: the action of coiling or twisting or winding together