PA2 may refer to: ALCO PA-2, a diesel locomotive French aircraft carrier PA2 (French: ; aircraft carrier 2), a cancelled ship of the French Navy Pad Abort Test 2, an Apollo program mission Paranormal Activity 2, a 2010 American supernatural horror film Pennsylvania's 2nd congressional district Pennsylvania Route 2, a former state route in Pennsylvania Pitcairn PA-2 Sesquiwing, a biplane The PA2, a type of rolling stock used on the PATH train in New York and New Jersey PA2 key, on the IBM 3270 keyboard pA2, a measure for potency of competitive receptor antagonists, see receptor antagonist and competitive inhibition