Saturation is one of three parameters, Hue, Saturation, and Intensity, conveyed in an analog composite video signal. Saturation refers specifically to how much color is present in an object or region within a video picture, ie if it's just a hint of green or if it's really deep green. Within the composite video signal, the amount of color saturation is represented by the amplitude of a color subcarrier sinewave added to the luminance (Intensity) signal. The phase of the sinewave determines the color hue, ie if it's red, blue, green, etc.

Mentioned in:
Video False Colorizer & Video Color Synthesizer Model 606S
Composite or S-Video, NTSC or PAL, to VGA Converter Model 4260
IRE, defined in terms of video