/ Dictionary / Index S subarachnoid: Meaning and Definition of Find definitions for: sub•a•rach•noid Pronunciation: (sub"u-rak'noid), [key] — adj. Anat. of, pertaining to, or situated below the arachnoid membrane. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. subaqueous subarachnoid block Related Content Daily Word Quiz: paradox Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language