·noun The arachnoid membrane.
II. Arachnoid ·noun One of the Arachnoidea.
III. Arachnoid ·adj Resembling a spider's web; cobweblike.
IV. Arachnoid ·adj Covered with, or composed of, soft, loose hairs or fibers, so as to resemble a cobweb; cobwebby.
V. Arachnoid ·adj Pertaining to a thin membrane of the brain and spinal cord, between the dura mater and pia mater.