Etym: A term originating around Leeds for a sheep-sized creature, sometimes in the form of a dog, said to haunt people who would shortly die.
Padma Patil: Etym: In Sanskrit, means the lotus, the symbol of enlightenment, and has various related meanings. In present-day usage, also the main channel of the Ganges River.
Pansy Parkinson: Etym: Viola tricolor aka heartsease. Signifies "thoughts", and the common name is derived from the French for "thought".
Paracelsus (PS ch. 6): The pseudonym of Philippus Aureolus Theophrastus Bombastus von Hohenheim (1493-1541), physician and alchemist, who established the role of chemistry in medicine, and was one of the first advocates of an empirical approach that became modern scientific method.
Parkinson, Pansy (PS ch. 7): A Slytherin in the same year as Harry.
Etym: From a diminutive of Peter.
Parselmouth: One who has the automatic ability to speak Parseltongue.
Etym: According to Rowling, it's an old word for someone who has a mouth-related deformity.
Parseltongue: The language of snakes.
Parvati Patil: Etym: EB: "The benevolent aspect of Shakti." Depending on which thread of Hinduism you follow, Shakti is either (a) the wife of Shiva, (b) a wife of Shiva, (c) the feminine, creative aspect of Shiva, (d) a personification of positive energy in general, or (e) all of the above but it doesn't matter since all definable things are illusion anyway.
Patil, Padma: A Ravenclaw, in the same year as Harry.
Etym: See below.
Patil, Parvati: A Gryffindor, same year as Harry.
Etym: From the Pictish peit "portion (of land)" and Gaelic tulach "hill". Alternatively, also a surname of Indian origin.
Patrick Delaney-Podmore: Etym: The name of the patron saint of Ireland, whose original name was Sucat. This name comes from Latin patricius, "nobleman". Also a Scottish variant of partridge.
Patronus Charm: A spell that invokes a guardian spirit to protect the caster; the primary means of defense against dementors. An essential component of the spell is focusing on a happy thought-- the happier the thought, the stronger the Patronus. Incantation: Expecto Patronum.
Peebles: A town on the England-Scotland border.
Peeves the Poltergeist: An obnoxious ghost inhabiting Hogwarts, teasing the students and irritating the staff and other ghosts. Controllable only by the teachers and the Bloody Baron.
Etym: Invented, as far as I can tell, from peeve.
Penelope Clearwater: Etym: The wife of Ulysses. When he was thought to be dead, she held off suitors by saying she must first finish weaving a shroud for Laertes. Each night, she would undo the weaving she had done that day, thus delaying them indefinitely. She has come to symbolize the chaste and faithful wife.
Pepper Imps: A magical candy which causes the eater to breathe smoke.
Peppermint Toad: A wizard candy.
Percy Weasley: Etym: A family name that dates back to William de Perci, a comrade of William the Conqueror.
Perenelle Flamel: Etym: I seem to recall this is a name for some kind of flower, but can't find any info. Anyone?
Perkins (CoS ch. 3): Along with Arthur Weasley, the staff of the Misuse of Muggle Artifacts Office.
Etym: From another variation of Peter, from the Greek for "stone".
Perks, Sally-Anne (PS ch. 7): A student of unknown house, in the same year as Harry.
Etym: Variation of park, which in the Middle Ages meant a large enclosed area used for game hunting.
Peskipiski Pesternomi: An incantation that Lockhart claimed would drive off Cornish pixies.
Etym: At a guess, mangled English: pesky-piskey pester-no-me. Piskey is a dialectual variant of pixie.
Peter Pettigrew: Etym: From the Greek petros "stone", a translation of the Aramaic Cephas.
Petrificatus Totalus: The incantation for the Body-Bind.
Etym: Latin-ish back-formation from petrify and total.
Pettigrew, Peter: One of James Potter's school friends, he became an Animagus with an animal form of a rat, which in retrospect really should have seen as some kind of warning. He later turned to the dark side and betrayed the Potters to Voldemort. When that unexpectedly resulted in Voldemort's fall, he faked his own death, cut off a finger to leave evidence framing Sirius Black for it, and took up a new life as Scabbers until Black hunted him down.
Etym: From Old French petit "little" and cru "growth", a nickname for a small man, or an old form of "pedigree".
Petunia Dursley: Etym: From petun, "tobacco"; the flower is in the tobacco family.
Philosopher's Stone: A substance representing the ideal combination of the essences of all elements, sought by alchemists down the ages, thought to make it possible to do all sorts of magical things. In these books, an actual stone which can be used to make the Elixir of Life.
phoenix: A mythical bird which lives 500 years and then dies, only to be reborn in a magical fire. Rowling's variant symbolizes love or loyalty. Phoenix feathers are used as wand cores, and phoenix tears have healing powers.
Phyllida Spore: Etym: Probably from Greek phyllos, meaning "leaf".
Piers Polkiss: Etym: A French variation of Peter.
Pigwidgeon: Ron's owl, given to him by Sirius Black and named by Ginny Weasley.
Etym: May be an alternate form of Pigwiggin, a fairy knight favored by Queen Mab, the wife of Oberon. Also, an archaic Scottish epithet.
Pince: The librarian at Hogwarts.
Etym: Variation of Pinch, a nickname for a chirpy person. Really.
Platform 9 3/4: The platform for the Hogwarts Express at King's Cross Station.
Pocket Sneakoscope: A magical device that spins and flashes when someone untrustworthy is present.
Podmore: see Delaney-Podmore.
Polkiss, Piers (PS ch. 2): Dudley Dursley's best friend and chief accomplice in tormenting Harry.
Etym: No etymology.
Polyjuice Potion: With the addition of a hair or other bit of someone, allows the drinker to take on the form of that person for one hour. Cannot be used for animal transformations.
Pomfrey, Poppy: The nurse at Hogwarts, for whom treating broken arms, catatonia, poison, and the like is a typical day's work.
Etym: Welsh name from the given name Humphrey, from the Germanic huun "bear cub" + frid "peace". (Alternately, OEW translates it as "peace through force".) St. Humphrey was a 9th century bishop of Therouanne.
Poppy Pomfrey: Etym: Various flowers of the genus Papaver. Signifies consolation or oblivion. Also, in the UK, worn to commemorate veterans of the World Wars.
Potions: A standard class at Hogwarts; taught by Professor Snape.
Potter, Harry: An orphaned wizard, unique among even his magically talented classmates in that dark forces really are constantly attacking him and causing him to miss class. Wand: 11", supple, holly and phoenix feather.
Etym: Stated by Rowling to be a name she just liked.
Potter, James: Harry's father, killed by Voldemort. In school, he was a Gryffindor and became Head Boy. He was also an Animagus, taking on the form of a stag. Wand: 11", pliable, mahogany.
Potter, Lily: Harry's mother, killed protecting Harry from Voldemort. She came from a Muggle family, was a Gryffindor and became Head Girl when she was at Hogwarts. Wand: 10 1/4", swishy, willow.
Prang, Ernie (PoA ch. 4): The driver of the Knight Bus.
Etym: Various meanings relating to crashing.
Predicting the Unpredictable: Insulating Yourself Against Shocks: A book in Flourish and Blotts.
prefect: A fifth-year or later student appointed by the teachers to take some responsibility for other students. There appears to be at least one prefect for each of the Hogwarts houses.
Prefects Who Gained Power: An engrossing book Percy picked up in Diagon Alley.
Prewetts (PS ch. 5): Wizards killed by Voldemort.
Etym: Diminutive form of a name from Middle English prou(s) "brave", "valiant".
Privet Drive: The street in Little Whinging where the Dursleys live. Privet is commonly used in hedges-- very much a feature of dull, conformist suburbia.
Prod, Warlock D. J., of Didsbury (CoS ch. 8): A satisfied Kwikspell customer.
Prongs: James Potter's nickname among his school buddies.
Pucey, Adrian (PS ch. 11): A Chaser for the Slytherin Quidditch team.
Etym: From a town in Berkshire.
puffer fish: Any of the ninety or so fishes of the family Tetradontidae. Their eyes are an ingredient in a Swelling Solution.
Pumpkin Pasties: A wizard candy, probably some kind of pastry with pumpkin filling.
pure-blood: Term for a wizard with no discernable Muggle or nonhuman ancestry. Used only by wizards who feel this sort of eugenic superiority gives them a divine right to rule others and operate outside the rules (as opposed to the actual divine right of Gryffindors to rule others and operate outside the rules).
Put-Outer: A magical device that can supress lights.