Phial - Containers used to hold potions or potion ingredients. Most commonly made of glass or crystal.

Phoenix - A large, red and gold bird. Instead of dying they burst into flames and are born again from the ashes. Their feathers are used as wand cores, their tears have healing powers, and they can carry heavy loads.

Pimple Jinx - Furnunculus. A jinx which causes a person to break out in boils. Can be cured by the Boil-Cure Potion.

Platform 9 3/4 - Platform from which the Hogwarts Express is caught. Hidden from the muggle world. It is accessed by running through the barrier between Platforms 9 and 10 at King's Cross Station in London.

Poison - Anything (can be a type of potion) that causes or enhances negative effects upon the body. The exact opposite of an antidote.

Poltergeist - A spirit but were never living humans. They tend to not have a physical form (the exception being Peeves) but are able to fly and interact with the world around them. They delight in vandalism, malicious mischief, and the aggravation and embarrassment of the living. They cannot be destroyed or driven from a location, but if they have a physical form they are vulnerable to some hexes.

Potion - A mixture or compound with magical properties. Can be liquid, solid or gas. See 'Mixture' and 'Compound'

Pumpkin Pastie - Pastry filled with pumpkin, similar to the muggle Cornish Pastie.

Put-Outer - See 'Deluminator'