AC vs alternating current

AC and alternating current both are nouns.

Word	Noun	Adjective	Verb	Adverb
AC	Yes	No	No	No
alternating current	Yes	No	No	No

As nouns, AC and alternating current are synonyms defined as:

AC and alternating current: an electric current that reverses direction sinusoidally

Other synonyms of AC include alternating electric current.

AC (noun)	alternating current (noun)
an electric current that reverses direction sinusoidally	an electric current that reverses direction sinusoidally