Dictionary Definition

arachnoid adj : relating to or resembling a member of the class Arachnida [syn: arachnidian, spidery, spiderlike, spiderly]

1 the middle of the 3 meninges [syn: arachnoid membrane]

2 air-breathing arthropods characterized by simple eyes and four pairs of legs [syn: arachnid]

User Contributed Dictionary

Relating to spiders.
Relating to the arachnoid mater, the middle layer of the meninges, the three membranes that protect the brain.

An arachnid
The arachnoid mater, the middle layer of the meninges, the three membranes that protect the brain
A round network of fractures in the crust of Venus
The mushroom has an arachnoid veil which is composed of many spider-web-like fibers.

The word Arachnoid means pertaining to or resembling an arachnid or spider. It may also refer to:

Arachnoid mater, one of the three layers of the meninges, a system of membranes that contain the central nervous system.
Arachnoid (astrogeology), a geological structure resembling a spider web, found only on the planet Venus