P

parallax scrolling (Full page here.) - The technique of moving (scrolling) multiple graphics layers at different speeds to create an illusion of depth.

password (Full page here.) - A group of letters, numbers or images given by a game for a specific purpose. Most passwords let players return to a later part of a game without having to play through the earlier parts again. Using password systems allowed game makers to let players save their place in a game without using a pricier battery backup method. Passwords mostly disappeared once system-based storage solutions became the norm for consoles and portable systems.

police (Full page here.) - Organization of individuals officially recognized by a state to enforce that state's laws.

Pow (item) (Full page here.) - Not to be confused with P.O.W. (Prisoner of War), POW is a power-up item symbolized by a large capital P with the letters o and w following in lower-case form. Its effects depend on the game and include things like improving a weapon, a smart bomb attack and transforming all enemies into helpful items.

Palette (Full page here.) - An ordered set of colors used by a piece of raster graphic data. Most sprites and other pixel-based game graphics are actually maps (bitmaps and pixmaps) and each pixel has a palette index color assigned to it. Example: if the pixel at column 4, row 2 (X:4, Y:2) is color 3, the system will draw it using the color in the third palette slot. (See much more in the full definition)

Palette Swap (Full page here.) - Graphic objects that use the exact same graphics as another object, but are colored differently through the use of an alternate palette. This allowed programmers to add more characters, items and stages without using precious memory space to add more sprites and tiles or more development time. Famous examples of this are Billy and Jimmy Lee from Double Dragon, the Lin Kuei ninja from Mortal Kombat and even the Ghost Monsters from Pac-Man.

Platformer (Full page here.) - These games place the player on an uneven playing field, causing the terrain itself to become part of the challenge. The game's goals must be achieved while reaching areas (or platforms) of different heights and travelling over gaps in the platforms.

power-up (Full page here.) - An item obtained during the game that has an effect (often positive, but sometimes negative) for the player.

Pro Wrestler (Full page here.) - A wrestler in the very specific sport and art of Professional Wrestling, where many of the rules of normal wrestling and other grappling sports need not apply (especially when the referee is distracted). In most video games, pro wrestlers in non-wrestling video games are usually set apart from the rest of the cast by possessing incredible strength, size and powerful grappling moves.

External Info sources and references:
CPS-2 Shock
System 16
Vidgame.net