Zebra Stripes: A feature of professional cameras, which places diagonal lines across any over-exposed parts of the picture in the viewfinder. These stripes will not show on the output/recorded picture, they are only there as a guide for the camera operator. More info: Zebra Stripes, Video camera viewfinders
Zone System: A photographic system which divides light into ten tonal steps, from Zone 0 (absolute black) to Zone IX (absolute white). Zone V is medium gray, the same value found on an 18% gray card.
Zoom: Framing movement, in which the focal length of the zoom lens is altered to make the subject appear closer to, or further away from the camera. Note that this effect is similar, but not the same as moving the camera itself closer to or further away from the subject. More info: Video Camera Zoom
Zoom Lens: A lens with a moveable element, which is able to "zoom" between various focal lengths. This has the effect of making the subject appear closer to, or further away from the camera. More info: Video Camera Zoom
Zoom Microphone: A microphone on a video camera which adjusts it's pickup pattern to match the zoom lens, i.e. the mic becomes more directional as the lens zooms in. Related info: Microphones
Zoom Ratio: A number indicating the zoom range of a lens, arrived at by dividing the shortest focal length into the longest focal length. A 10 to 100 mm zoom has a zoom ratio of 10x. The number is sometimes stated as a ratio, e.g. 10:1.