noun

• (anatomy) The pia mater, the innermost of the meninges that protect the brain and spinal cord.
• A perennial Polynesian herb whose fleshy tubers yield arrowroot.
• (linguistics) Initialism of Proto-Indo-Aryan. [The reconstructed proto-language —having descended from Proto-Indo-Iranian— that is the immediate predecessor of Old Indo-Aryan.]
• (medicine) Initialism of porcine intestinal adenomatosis.
• Initialism of personal injury accident.
• (sexuality) Initialism of penis in anus.
• Initialism of privacy impact assessment.