/ Dictionary / Index A arachnoid: Meaning and Definition of Find definitions for: a•rach•noid Pronunciation: (u-rak'noid), [key] — adj. resembling a spider's web. of or belonging to the arachnids. of or pertaining to the arachnoid membrane. formed of or covered with long, delicate hairs or fibers. —n. an arachnid. the serous membrane forming the middle of the three coverings of the brain and spinal cord. Cf. dura mater, meninges, pia mater. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. See also: arachnoid (Thesaurus) arachnid Arad Related Content Daily Word Quiz: fresco Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language