Source : Webster's Revised Unabridged Dictionary (1913)

Cortical \Cor"ti*cal\ (k?r"t?-kal), a. [L. cortex bark: cf. F.
   cortical.]
   Belonging to, or consisting of, bark or rind; resembling bark
   or rind; external; outer; superficial; as, the cortical
   substance of the kidney.

Source : WordNet®

cortical
     adj : of or relating to a cortex