Definition from Wiktionary, the free dictionary
subarachnoid (not comparable)
- (medicine) Located or occurring below the arachnoid mater, often specifically between the arachnoid membrane and the pia mater
1988 May 20, Jack Clark, “Touch of Death”, Chicago Reader:
- After an internal examination he found that "the cause of death was craniocerebral injury with subarachnoid hemorrhage […] ."