Source : Webster's Revised Unabridged Dictionary (1913)

Peritoneal \Per`i*to*ne"al\, a. [Cf. F. p['e]riton['e]al.]
   (Anat.)
   Of or pertaining to the peritoneum.

Source : WordNet®

peritoneal
     adj : of or relating to or affecting the peritoneum; "peritoneal
           cancer"