Arachnid a

a-rak′ni-da, n.pl. a sub-cla of Tracheate Arthropod a, embracing spiders, scorpions, mites, ., first separated by Lamarck from the Insect a of Linnæus.— adj. Arach′nid an .— n. and adj. Arach′noid , like a cobweb.— adjs. Arachnoi′dal , A rach no log′ical .— n. Arachno′logist , one who devotes himself to the study of arachnid a.— Arachnoid membrane , one of the three coverings of the brain and spinal cord, situated between the dura-mater and the pia-mater, non-vascular, transparent, thin. [Gr. arachnē , spider.]