Kelvin: A unit of temperature measurement. Colour is measured in kelvins. More info: Color temperature
Key Frame: In some forms of digital compression, uncompressed frames (key frames) are placed at regular intervals (eg. every 6th frame is uncompressed). Each subsequent frame exists as variations on the keyframe, until a new keyframe is introduced. The further apart the keyframes, the worse the overall picture quality.
Key Grip: Person in sharge of constructing and dismantling film sets and dolly tracks. Related info: Jobs in Film