ARACHNOID

I. adjective Date: 1789 of or relating to a thin membrane of the brain and spinal cord that lies between the dura mater and the pia mater, covered with or composed of soft loose hairs or fibers, II. noun Etymology: New Latin ~es, from Greek arachnoeidēs, like a cobweb, from arachnē spiderweb Date: circa 1847 an ~ membrane, III. adjective Etymology: New Latin Arachnida + English -oid Date: 1852 resembling or related to the arachnids