arachnoid

1 of 3

adjective (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 3

noun

: an arachnoid membrane

arachnoid

3 of 3

adjective (2)

: resembling or related to the arachnids

Examples of arachnoid in a Sentence

Recent Examples on the Web

Adjective

Since then, the arachnoid warrior (voiced by Shameik Moore) has grown into his powers and superhero responsibilities. —Lovia Gyarkye, The Hollywood Reporter, 31 May 2023

Noun

At Children's Minnesota, Dr. Kyle Halvorson said arachnoid cysts are more commonly found in a patient's head, but rarely by the spinal column. —Kelly Smith, Star Tribune, 24 Mar. 2021

In 2018, Meyer retired from the Ohio State job, citing health concerns, including headaches related to a congenital arachnoid cyst. —New York Times, 14 Jan. 2021

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 2 adjective

variants also arachnoidal

ə-ˌrak-ˈnȯid-ᵊl 

: of or relating to the arachnoid

the arachnoid membrane