undulation vs undulate

undulation is a noun but undulate is not a noun.

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

undulation (noun)	undulate (noun)
(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

undulation (adjective)	undulate (adjective)
	having a wavy margin and rippled surface

undulation (verb)	undulate (verb)
	increase and decrease in volume or pitch, as if in waves
	move in a wavy pattern or with a rising and falling motion
	stir up (water) so as to form ripples
	occur in soft rounded shapes