Why is a
floppy "disk", but a CD-ROM "disc"?
Well don't hold out!
Tell us! :)
DisC is for audio, DisK is for computers.
Since the Compact Disc is an AUDIO media, it is called DisC. When used
on Data, the name wasn't changed.
Apple has a different view on that, more reasonable:
http://support.apple.com/kb/HT2300
It says that DisC is for optical media and DisK is for magnetic (and
enclosured) media. Very reasonable.
Wikipedia says the same:
http://en.wikipedia.org/wiki/Spelling_of_disc
Quoting: "Generally in computer terminology, disk refers to magnetic
storage while disc refers to optical storage."
So, I stick with apple's (and wikipedia) idea, although wikipedia has a
better explanation about the subject.