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

Moby Thesaurus II by Grady Ward, 1.0:

149 Moby Thesaurus words for "convolution":
   Barnumism, aduncity, affectation, aquilinity, arachnoid,
   arbor vitae, arching, archipallium, arcuation, bedizenment,
   between brain, big talk, brain stem, cerebellar hemispheres,
   cerebellum, cerebral cortex, cerebrospinal fluid, cerebrum,
   circularity, complexity, complexness, complication, concameration,
   concavity, convexity, corpus callosum, corpus striatum,
   crabbedness, crookedness, curvation, curvature, curving, curvity,
   decurvation, decurvature, diencephalon, dura mater, endbrain,
   entanglement, excurvation, excurvature, fissure, flashiness,
   flatulence, flatulency, folia, forebrain, fornix, frontal lobe,
   fulsomeness, garishness, gaudiness, glial cells, globus pallidus,
   grandiloquence, grandioseness, grandiosity, gray matter, gyrus,
   high-flown diction, hindbrain, hippocampus, hookedness,
   hypothalamus, incurvation, incurvature, incurvity, inflatedness,
   inflation, intricacy, intricateness, involution, involvement,
   lenticular nucleus, lexiphanicism, limbic lobe, little brain, lobe,
   loftiness, luridness, magniloquence, mantle, medulla oblongata,
   meninges, mere rhetoric, meretriciousness, mesencephalon,
   metencephalon, midbrain, myelencephalon, neopallium,
   occipital lobe, optic chiasm, orotundity, ostentation,
   ostentatious complexity, pallium, parietal lobe, perplexity,
   pia mater, pineal body, pituitary body, platitudinous ponderosity,
   polysyllabic profundity, pomposity, pompous prolixity, pompousness,
   pons, pontification, pretension, pretentiousness, prose run mad,
   ramification, recurvation, recurvature, recurvity,
   reticular system, rhetoric, rhetoricalness, rhombencephalon,
   rondure, rotundity, sensationalism, sententiousness, showiness,
   sinuosity, sinuousness, stiltedness, subthalamus, subtlety,
   swelling utterance, swollen phrase, swollenness, tall talk,
   tanglement, technicality, telencephalon, temporal lobe, thalamus,
   tortuosity, tortuousness, tumidity, tumidness, turgescence,
   turgidity, vaulting, ventricle, vermis, white matter