pa or PA may stand for:

• pa, a word for dad or father ("pa" or "paw")
• Pa, Maori word meaning a fortified village or redoubt , described at length in Maori Wars
• Palestinian Authority
• Panama (ISO country code, PA)
• Panjabi language (ISO 639 alpha-2, pa)
• pascal (Pa), SI unit of pressure
• Pennsylvania, the US state
• Penny Arcade, the popular gaming webcomic
• Personal Assistant (PA)
• physician assistant, the medical profession
• protactinium (Pa), symbol for the chemical element
• Port Angeles a city in Washington State in the United States
• Polyamide (PA), a kind of plastic
• Polyacetylene (PA)
• Public Address System system amplification equipment
• Phillips Academy, a private secondary school
• PA is the IATA alpha code designator for Pan American World Airways (Pan Am)
• PA is also the short form for the PA-RISC family processor architecture from Hewlett-Packard