The Collaborative International Dictionary of English v.0.48:
Gyral \Gy"ral\ (j[imac]"ral), a. [See Gyre.] 1. Moving in a circular path or way; whirling; gyratory. [1913 Webster] 2. (Anat.) Pertaining to a gyrus, or convolution. [1913 Webster]WordNet (r) 3.0 (2006):
gyral adj 1: relating to or associated with or comprising a convolution of the brain; "the gyral sulcus"