megacycle vs MHz

megacycle and MHz both are nouns.

Word	Noun	Adjective	Verb	Adverb
megacycle	Yes	No	No	No
MHz	Yes	No	No	No

As nouns, megacycle and MHz are synonyms defined as:

Other synonyms of megacycle include Mc, megacycle per second, megahertz.

megacycle (noun)	MHz (noun)
one million periods per second	one million periods per second