In papermaking, abbreviation for cross-machine direction. See Cross-Machine Direction.
CD is also an abbreviation for compact disc, used to refer to both compact disc digital audio (or audio CD) or compact disc-read only memory. See Compact Disc.
In networking, CD is also an abbreviation for collision detection. See Carrier Sense Multiple Access/Collision Detection.
In telecommunications, CD is also an abbreviation for carrier detect. See Carrier Detect.