This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. Of or pertaining to the ischium

adj. Same as ischial.

Of or pertaining to the ischium; sciatic. Also ischiadic, ischial.

"Look at the flat, narrow haunch bones — the long and narrow passage — the coarse, outwardly curved, ischiatic prominences on which the Gibbon habitually rests, and which are coated by the so-called “callosities,” dense patches of skin, wholly absent in the Gorilla, in the Chimpanzee, and in the"

ischiatic symphysis   

ischial