1. plural of arachnoid; the middle membrane covering the brain and spinal cord
Usage: medical; anatomy

Examples

• The surgeon carefully examined the arachnoids during the brain operation.
• Inflammation of the arachnoids can cause severe headaches.
• The arachnoids lie between the dura mater and pia mater.
• Damage to the arachnoids may result in cerebrospinal fluid leakage.
• Medical students learn about the three layers protecting the brain, including the arachnoids.