A-rāch'noid, a.
[Gr. ἀραχνοειδής, like a cobweb, from ἀράχνη, spider, spider's web, and εἶδος, form.]
Sense 1. Resembling a spider's web.
Sense 2. (Anat.) Pertaining to a thin, semi-transparent membrane of the brain, between the dura mater and pia mater. Dunglison.
☞ The same term was applied by Celsius and Galen to the membrane of the vitreous humor of the eye.
Sense 3. (Bot.) Covered with, or composed of, soft, loose hairs or fibers, so as to resemble a cobweb; cobwebby. Gray.