1. Plural of pia; the innermost membrane enveloping the brain and spinal cord.
Usage: medical/anatomical term; usually used in the phrase 'pia mater'

Examples

• The pias are delicate membranes that protect the central nervous system.
• Inflammation of the pias can lead to serious neurological complications.
• The doctor examined the pias during the surgical procedure.
• The pias mater is the innermost of the three meninges.