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

The researchers tracked antigens and other substances crossing the arachnoid barrier, an obstacle that’s known for its impermeability but which, they found, leaks in this particular area.

From Quanta Magazine

He coped for two decades with headaches caused by an arachnoid cyst in his brain.

From Washington Post

The arachnoid has also shown slight congestion, and in other cases the membranes showed a slight thickening.

From Project Gutenberg

The lymph was purely basal, solely on the arachnoid, not in the fissures or sulci.

From Project Gutenberg

In quite young specimens the collector will notice two well defined arachnoid veils, the lower one being much more dense.

From Project Gutenberg

From its resemblance to a spider's web such a veil is said to be arachnoid.

From Project Gutenberg

Let them form arachnoid associations, spinsters and spiders would be a good motto.

From Project Gutenberg