gigacycle per second vs gigacycle

gigacycle per second and gigacycle both are nouns.

Word	Noun	Adjective	Verb	Adverb
gigacycle per second	Yes	No	No	No
gigacycle	Yes	No	No	No

As nouns, gigacycle per second and gigacycle are synonyms defined as:

Other synonyms of gigacycle per second include Gc, GHz, gigahertz.

gigacycle per second (noun)	gigacycle (noun)
1,000,000,000 periods per second	1,000,000,000 periods per second