gravitation wave vs undulation

gravitation wave and undulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
gravitation wave	Yes	No	No	No
undulation	Yes	No	No	No

As nouns, undulation is a hypernym of gravitation wave; that is, undulation is a word with a broader meaning than gravitation wave:

gravitation wave: (physics) a wave that is hypothesized to propagate gravity and to travel at the speed of light
undulation: (physics) a movement up and down or back and forth

Other hypernyms of gravitation wave include wave.

gravitation wave (noun)	undulation (noun)
(physics) a wave that is hypothesized to propagate gravity and to travel at the speed of light	(physics) a movement up and down or back and forth
	wavelike motion; a gentle rising and falling in the manner of waves
	an undulating curve