decameter vs dekametre

decameter and dekametre both are nouns.

Word	Noun	Adjective	Verb	Adverb
decameter	Yes	No	No	No
dekametre	Yes	No	No	No

As nouns, decameter and dekametre are synonyms defined as:

Other synonyms of decameter include dam, decametre, dekameter, dkm.

decameter (noun)	dekametre (noun)
a metric unit of length equal to ten meters	a metric unit of length equal to ten meters