arachnoid membrane n.
A delicate fibrous membrane forming the middle of the three coverings of the brain and spinal cord, closely attached to the dura mater, from which it is separated only by the subdural cleft, but separated from the pia mater by the subarachnoid space.
|the middle of the 3 meninges [syn: arachnoid]|
|a children's mummer's parade, as on the Fourth of July, with prizes for the best costumes.|
|a screen or mat covered with a dark material for shielding a camera lens from excess light or glare.|