Source : Webster's Revised Unabridged Dictionary (1913)

Gyral \Gy"ral\, a. [See {Gyre}.]
   1. Moving in a circular path or way; whirling; gyratory.

   2. (Anat.) Pertaining to a gyrus, or convolution.

Source : WordNet®

gyral
     adj : relating to or associated with or comprising a convolution
           of the brain; "the gyral sulcus"