cycles/second vs cycle per second

cycles/second and cycle per second both are nouns.

Word	Noun	Adjective	Verb	Adverb
cycles/second	Yes	No	No	No
cycle per second	Yes	No	No	No

As nouns, cycles/second and cycle per second are synonyms defined as:

cycles/second and cycle per second: the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)

Other synonyms of cycles/second include cps, cycle, hertz, Hz.

cycles/second (noun)	cycle per second (noun)
the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)	the unit of frequency; one hertz has a periodic interval of one second (named for Heinrich Rudolph Hertz)