1. resembling a spider or spider’s web; having a thin, delicate, web-like structure

1. the middle membrane covering the brain and spinal cord, located between the dura mater and pia mater
Usage: medical; anatomy

Examples

• The arachnoid membrane protects the brain from injury.
• Doctors examined the arachnoid layer during the surgery.
• The delicate arachnoid structure was visible under the microscope.
• An arachnoid cyst can cause headaches if it grows large.
• The spider’s web had an arachnoid appearance in the morning dew.
• Medical students learn about the three layers: dura mater, arachnoid, and pia mater.