P31 may refer to:
Aircraft
*
Boulton Paul P.31 Bittern, a British prototype fighter aircraft
*
Curtiss XP-31 Swift, an American experimental fighter aircraft
*
Percival P.31 Proctor, a British radio trainer and communications aircraft
Vessels
* , a corvette of the Argentine Navy
* , a submarine of the Royal Navy
* , a corvette of the Indian Navy
* , a ship of the Irish Naval Service
* , of the Armed Forces of Malta
Other uses
*
Makhuwa language
*
Papyrus 31
Papyrus 31 (in the Gregory-Aland numbering), designated by 𝔓31, is an early copy of the New Testament in Greek. It is a papyrus manuscript of the Epistle to the Romans, it contains only Romans 12:3-8. The manuscript paleographically has been ...
, a biblical manuscript
*
Phosphorus-31 (P-31 or
31P), a stable isotope of phosphorus
*
Pioneer P-31
Pioneer P-31 (also known as Atlas-Able 5B or Pioneer Z) was intended to be a lunar orbiter probe, but the mission failed shortly after launch. The objectives were to place a highly instrumented probe in lunar orbit, to investigate the environmen ...
, a failed lunar probe
* P31, a
state regional road in Latvia
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