Wiktionary
n. (context anatomy English) The space between the arachnoid mater and the pia mater that surround the brain and spinal cord.
WordNet
n. a space in the meninges beneath the arachnoid membrane and above the pia mater that contains the cerebrospinal fluid
Wikipedia
SubArachnoid Space was a San Francisco, California-based psychedelic rock band founded in 1996 by Mason Jones, the owner of the independent music label Charnel Music. Initially the band was a trio (Mason Jones: guitar, Jason Stein: bass, Michelle Schreiber: drums) and the debut 7" single release was by the trio. Before the band's first live show, performed at KFJC radio, second guitarist Melynda Jackson joined. That quartet toured for a few years before Michelle moved to Texas and Chris Van Huffle joined as drummer. The role of bassist shifted several times from that point on but the rest of the lineup remained consistent until 2003, when Mason left the group so they could tour more. Shortly thereafter the band's core of Melynda and Chris relocated to Portland Oregon, where they continued to perform, tour and release albums. The band completed a fall tour of the US with the Italian group OVO in September/October 2009 before disbanding on August 13, 2010. This was accompanied by a farewell show at Mississippi studios. Melynda Jackson and Chris Van Huffle went on to form Eight Bells.
Usage examples of "subarachnoid space".
Even the membranes, taken by themselves, are not sufficient protection for the brain: between tbe arachnoid membrane and the pia mater (the subarachnoid space) is the final touch, the cerebrospinal fluid.