km/h vs kilometres per hour

km/h and kilometres per hour both are nouns.

Word	Noun	Adjective	Verb	Adverb
km/h	Yes	No	No	No
kilometres per hour	Yes	No	No	No

As nouns, km/h and kilometres per hour are synonyms defined as:

km/h and kilometres per hour: the ratio of the distance traveled (in kilometers) to the time spent traveling (in hours)

Other synonyms of km/h include kilometers per hour, kph.

km/h (noun)	kilometres per hour (noun)
the ratio of the distance traveled (in kilometers) to the time spent traveling (in hours)	the ratio of the distance traveled (in kilometers) to the time spent traveling (in hours)