compact disc vs compact disk

compact disc and compact disk both are nouns.

Word	Noun	Adjective	Verb	Adverb
compact disc	Yes	No	No	No
compact disk	Yes	No	No	No

As nouns, compact disc and compact disk are synonyms defined as:

compact disc and compact disk: a digitally encoded recording on an optical disk that is smaller than a phonograph record; played back by a laser

Other synonyms of compact disc include CD.

compact disc (noun)	compact disk (noun)
a digitally encoded recording on an optical disk that is smaller than a phonograph record; played back by a laser	a digitally encoded recording on an optical disk that is smaller than a phonograph record; played back by a laser