gyrus

from WordNet (r) 3.0 (2006)

gyrus
    n 1: a convex fold or elevation in the surface of the brain
         [syn: {gyrus}, {convolution}]

from The Collaborative International Dictionary of English v.0.48

Gyrus \Gy"rus\ (j[imac]"r[u^]s), n.; pl. {Gyri}
   (j[imac]"r[imac]). [L. See {Gyre}, n.]
   A convoluted ridge between grooves; a convolution; as, the
   gyri of the brain; the gyri of brain coral. See {Brain}.
   [1913 Webster]