arachnoid

[ uh-rak-noid ]

adjective

1. resembling a spider's web.
2. of or belonging to the arachnids.
3. Anatomy. of or relating to the arachnoid membrane.
4. Botany. formed of or covered with long, delicate hairs or fibers.

noun

1. an arachnid.
2. Anatomy. the serous membrane forming the middle of the three coverings of the brain and spinal cord.

arachnoid

/ əˈræknɔɪd /

noun

1. the middle of the three membranes that cover the brain and spinal cord See meninges
2. another name for arachnid

adjective

1. of or relating to the middle of the three meninges
2. botany consisting of or covered with soft fine hairs or fibres
3. of or relating to the arachnids

arachnoid

/ ə-răk′noid′ /

1. The delicate membrane that encloses the spinal cord and brain and lies between the pia mater and dura mater.

Word History and Origins

Origin of arachnoid¹

1745–55; < New Latin arachnoīdes < Greek arachnoeidḗs cobweblike. See arachnid, -oid

Example Sentences

Like with the MRI experiments, fluid containing these light-emitting molecules was seen to slip through the arachnoid barrier where blood vessels passed through.

From Science Daily

The meninges comprise three layers that surround the brain: pia, arachnoid and dura.

From Salon

He stepped down at Ohio State in 2018 mostly because of a congenital arachnoid cyst in his brain, which required surgery in 2014 and bothered him throughout his final season with the Buckeyes.

From Washington Times

The 54-year-old Meyer has an arachnoid cyst in his brain that causes severe headaches, and had shown obvious effects of being in pain on the sideline this season.

From Washington Times

Such drive was worrisome when combined with the headaches Meyer has suffered intermittently for two decades, caused by an arachnoid cyst in his brain.

From Washington Post