[ uh-rak-noid ]

  1. resembling a spider's web.

  2. of or belonging to the arachnids.

  1. Anatomy. of or relating to the arachnoid membrane.

  2. Botany. formed of or covered with long, delicate hairs or fibers.

  1. an arachnid.

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

Origin of arachnoid

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

Words Nearby arachnoid Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

How to use arachnoid in a sentence

British Dictionary definitions for arachnoid


/ (əˈræknɔɪd) /

  1. the middle of the three membranes that cover the brain and spinal cord: See meninges

  2. another name for arachnid

  1. of or relating to the middle of the three meninges

  2. botany consisting of or covered with soft fine hairs or fibres

  1. of or relating to the arachnids

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for arachnoid


[ ə-răknoid′ ]

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

The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.