arachnoid
1 of 3adjective (1)
arach·noid ə-ˈrak-ˌnȯid 
1
: of or relating to a thin membrane of the brain and spinal cord that lies between the dura mater and the pia mater
2
: covered with or composed of soft loose hairs or fibers
arachnoid
2 of 3noun
: an arachnoid membrane
arachnoid
3 of 3adjective (2)
: resembling or related to the arachnids
Word History
Etymology
Noun
New Latin arachnoides, from Greek arachnoeidēs, like a cobweb, from arachnē spiderweb
Adjective (2)
New Latin Arachnida + English -oid
First Known Use
Adjective (1)
1789, in the meaning defined at sense 1
Noun
1804, in the meaning defined above
Adjective (2)
1825, in the meaning defined above
Medical Definition
arachnoid 1 of 2
noun
arach·noid ə-ˈrak-ˌnȯid
: a thin membrane of the brain and spinal cord that lies between the dura mater and the pia mater
arachnoid
2 of 2adjective
variants also arachnoidal
ə-ˌrak-ˈnȯid-ᵊl
: of or relating to the arachnoid
the arachnoid membrane