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Pakistan (ISO country code PK)

Pakistan International Airlines (IATA airline code PK)

Paperinik

Park (map abbreviation)

Parkour, an extreme sport

Peak (map abbreviation)

Penalty kick, in association football (soccer)

Pharmacokinetics

PK machine gun

Placekicker, in American football

Player killer (in MMORPGs, MUDs and other computer role-playing games)

Polyteknikkojen Kuoro, a Finnish academic male choir

Possum Kingdom Lake, Texas

Power Kick

Preacher's kid; pastor's kid; priest's kid (in the Anglican and Eastern Orthodox denominations); or, occasionally, prophet's kid (generally a tongue-in-cheek reference)

Primary key

Probability of kill (often used in simulation)

Promise Keepers, a Christian men's organization

Psychokinesis

Public-key cryptography

Public Knowledge

Puk Kai, an alternative form for a Cantonese foul phrase (仆街), meaning 'damn it!' or 'damned person'

Pick-off, in baseball

pK, negative logarithm of the dissociation constant K (-logK)

A brand of chewing gum, manufactured by Wrigley's.