Z: Used to indicate impedance.
Z-adjustment: Movement perpendicular to the plane of the X-Y axes. Specifically in an overhead projector, the lamp adjustment to reduce colour fringing when magnification and projection distance are changed.
Z-axis: (1) Intensity modulation of an oscilloscope. (2) In computer graphics, the third dimension indicating depth.
Z-clipping: In 3D computer graphics, limiting the depth of the three dimensional space in front and behind the screen by defining a hither plane and a yon plane, both parallel to the viewing plane.
zenith: In magnetic tape recording, the extent to which the head surface is parallel to the tape. Any error will cause uneven head wear and may cause the tape move up or down in an audio tape recorder ...