rocket vs test rocket

rocket and test rocket both are nouns.

Word	Noun	Adjective	Verb	Adverb
rocket	Yes	No	Yes	No
test rocket	Yes	No	No	No

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

rocket (noun)	test rocket (noun)
a jet engine containing its own propellant and driven by reaction propulsion	a rocket fired for test purposes
any vehicle self-propelled by a rocket engine
sends a firework display high into the sky
propels bright light high in the sky, or used to propel a lifesaving line or harpoon
erect European annual often grown as a salad crop to be harvested when young and tender

rocket (verb)	test rocket (verb)
propel with a rocket
shoot up abruptly, like a rocket