From The Free On-line Dictionary of Computing (19 January 2023):
cd
1. <operating system> change directory.
2. <networking> The country code for the Democratic Republic
of the Congo (formerly Zaire, zr).
(1999-01-27)
From The Free On-line Dictionary of Computing (19 January 2023):
Compact Disc
CD
<storage> (CD) (Not "disk", this spelling is part of the
standard).
A 4.72 inch disc developed by Sony and Philips that can
store, on the same disc, still and/or moving images in
monochrome and/or color; stereo or two separate sound tracks
integrated with and/or separate from the images; and digital
program and information files.
The same fabrication process is used to make both audio CDs
and CD-ROMs for storing computer data, the only difference
is in the device used to read the CD (the player or drive).
CD Information Center
(http://cd-info.com/cd-info/CDInfoCenter.html).
(1999-06-23)