cockle vs undulate

cockle is a noun but undulate is not a noun.

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

As verbs, cockle and undulate are synonyms defined as:

Other synonyms of cockle include riffle, ripple, ruffle.

cockle (noun)	undulate (noun)
common edible, burrowing European bivalve mollusk that has a strong, rounded shell with radiating ribs
common edible European bivalve

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

cockle (verb)	undulate (verb)
to gather something into small wrinkles or folds	increase and decrease in volume or pitch, as if in waves
stir up (water) so as to form ripples	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