trooper vs cuirassier

trooper and cuirassier both are nouns.

Word	Noun	Adjective	Verb	Adverb
trooper	Yes	No	No	No
cuirassier	Yes	No	No	No

As nouns, cuirassier is a hyponym of trooper; that is, cuirassier is a word with a more specific, narrower meaning than trooper:

Other hyponyms of trooper include dragoon, hussar, lancer, Rough Rider.

trooper (noun)	cuirassier (noun)
a mounted police officer	a cavalryman equipped with a cuirass
a soldier in a motorized army unit
a state police officer
a soldier mounted on horseback