seiche vs undulation

seiche and undulation both are nouns.

Word	Noun	Adjective	Verb	Adverb
seiche	Yes	No	No	No
undulation	Yes	No	No	No

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

seiche: a wave on the surface of a lake or landlocked bay; caused by atmospheric or seismic disturbances
undulation: (physics) a movement up and down or back and forth

Other hypernyms of seiche include wave.

seiche (noun)	undulation (noun)
a wave on the surface of a lake or landlocked bay; caused by atmospheric or seismic disturbances	(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