• WordNet 3.6
    • adj arachnoid relating to or resembling a member of the class Arachnida
    • n arachnoid air-breathing arthropods characterized by simple eyes and four pairs of legs
    • n arachnoid the middle of the 3 meninges
    • ***
Webster's Revised Unabridged Dictionary
    • Arachnoid (Bot) Covered with, or composed of, soft, loose hairs or fibers, so as to resemble a cobweb; cobwebby.
    • Arachnoid (Zoöl) One of the Arachnoidea.
    • Arachnoid (Anat) Pertaining to a thin membrane of the brain and spinal cord, between the dura mater and pia mater.
    • Arachnoid Resembling a spider's web; cobweblike.
    • Arachnoid (Anat) The arachnoid membrane.
    • ***
Century Dictionary and Cyclopedia
    • arachnoid Of or pertaining to the Arachnida; arachnidan.
    • arachnoid Like or likened to a cobweb: applied, in anatomy— to the arachnoid of the brain (see II.);
    • arachnoid to the hyaloid membrane or arachnoid of the eye (see II.).
    • n arachnoid A kind of fossil madrepore.
    • n arachnoid In anatomy, the serous membrane enveloping the brain and spinal cord; the middle one of the three cerebrospinal meninges, between the dura mater and the pia mater. It was formerly regarded as consisting of two layers, a visceral layer investing the pia mater and a reflected parietal layer lining the dura mater, the two constituting a shut sac, like other serous membranes, inclosing a cavity called the arachnoid cavity, containing a serous fluid, the arachnoid fluid; but the more modern view regards the arachnoid membrane as a single sheet external to the pia mater and attached to it, but not following it into the sulci and other depressions of the brain. What was formerly called the cavity of the arachnoid is now termed the subdural space. The arachnoid is by some regarded as simply the outermost layer of the pia mater. Also called arachnoid membrane, arachnoidea, arachnoides, and araneous membrane.
    • n arachnoid An old and disused name of the hyaline or hyaloid membrane within the eyeball, especially of that portion of it which contributes to form the capsule of the crystalline lens.
    • ***
Chambers's Twentieth Century Dictionary
    • n., adj Arachnoid like a cobweb
    • ***


Webster's Revised Unabridged Dictionary
Gr. like a cobweb; spider, spider's web + e'i^dos form


In literature:

Let them form arachnoid associations, spinsters and spiders would be a good motto.
"The Poet at the Breakfast Table" by Oliver Wendell Holmes, Sr.
The arachnoid is a thin membrane which lies beneath the dura mater.
"A Practical Physiology" by Albert F. Blaisdell
Thus, one layer of the arachnoid envelopes the brain and spinal cord, and the other lines the dura mater.
"The People's Common Sense Medical Adviser in Plain English" by R. V. Pierce
There may be effusion under arachnoid, into ventricles, at base of the brain, and around the cord.
"Aids to Forensic Medicine and Toxicology" by W. G. Aitchison Robertson
Arachnoideous: resembling or similar to a cobweb.
"Explanation of Terms Used in Entomology" by John. B. Smith
Neither is the arachnoid often affected with acute inflammation, except as a secondary result.
"Special Report on Diseases of the Horse" by United States Department of Agriculture
Water was found between the dura and pia mater, and between the pia mater and arachnoides.
"Cases of Organic Diseases of the Heart" by John Collins Warren
In quite young specimens the collector will notice two well defined arachnoid veils, the lower one being much more dense.
"The Mushroom, Edible and Otherwise" by M. E. Hard
Brain injected in its arachnoid coat.
"North American Medical and Surgical Journal, Vol. 2, No. 3, July, 1826" by Various
Describe the arachnoid membrane.
"A Treatise on Anatomy, Physiology, and Hygiene (Revised Edition)" by Calvin Cutter
Plant exhibiting the cortina unbroken, the extremities of its delicate arachnoid threads attached to cap and stem, respectively.
"Student's Hand-book of Mushrooms of America, Edible and Poisonous" by Thomas Taylor
Meanwhile, we're disgorging the arachnoid membranes with cowld applications, and we're relievin' the cerebellum by repose.
"The Fortunes Of Glencore" by Charles James Lever
The tunica arachnoides had generally lost its transparency, and was considerably thickened.
"Observations on Insanity" by John Haslam
On examination pus was found between the arachnoid and the pia mater.
"A System of Practical Medicine by American Authors, Vol. I" by Various
The arachnoid has also shown slight congestion, and in other cases the membranes showed a slight thickening.
"Barium, A Cause of the Loco-Weed Disease" by Albert Cornelius Crawford

In news:

Long-term follow-up of a multiloculated arachnoid cyst of the middle cranial fossa.
Abstract Arachnoid cysts are benign intracranial lesions that are typically diagnosed incidentally.
Subdural hematoma involving congenital arachnoid cyst.
Fans will be delighted to know that the open ending guarantees another sequel, another villain, and of course, more arachnoid antics.
Epidural Steroid Injection Risks Include Incurable Arachnoiditis.

In science:

All samples were prepared and tested at a room temperature ~ 22 oC and relative humidity of 55 – 65%. The dura and arachnoid were removed and the cerebral hemispheres were first split into right and left halves by cutting through the corpus callosum.
Mechanical Characterization of Brain Tissue in Compression at Dynamic Strain Rates