/ Thesaurus / S Synonyms of subarachnoid space Find synonyms for: Noun1. subarachnoid space, spaceusage: a space in the meninges beneath the arachnoid membrane and above the pia mater that contains the cerebrospinal fluidWordNet 3.0 Copyright © 2006 by Princeton University. All rights reserved. Related Content Daily Word Quiz: denizen Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language