The sixteenth letter of the Greek alphabet, Π/π.

The circle constant, ratio of circumference to diameter, about 3.14159.

Printing: to spill, jumble, or mix movable type.

Typography: non-Roman or special symbols outside the standard set.

An initialism with multiple meanings.

• private investigator
• principal investigator
• personal injury
• politically incorrect
• processing instruction
• phosphatidylinositol
• protease inhibitor
• polyimide
• power integrity
• parallel import
• port injection
• pro forma invoice