gravity-assist vs trajectory

gravity-assist and trajectory both are nouns.

Word	Noun	Adjective	Verb	Adverb
gravity-assist	Yes	No	No	No
trajectory	Yes	No	No	No

As nouns, trajectory is a hypernym of gravity-assist; that is, trajectory is a word with a broader meaning than gravity-assist:

gravity-assist: (spaceflight) a trajectory that passes close to a planetary body in order to gain energy from its gravitational field
trajectory: the path followed by an object moving through space

Other hypernyms of gravity-assist include flight.

gravity-assist (noun)	trajectory (noun)
(spaceflight) a trajectory that passes close to a planetary body in order to gain energy from its gravitational field	the path followed by an object moving through space