battlement vs crenel

battlement and crenel both are nouns.

Word	Noun	Adjective	Verb	Adverb
battlement	Yes	No	No	No
crenel	Yes	No	Yes	No

battlement (noun)	crenel (noun)
a rampart built around the top of a castle with regular gaps for firing arrows or guns	a notch or open space between two merlons in a crenelated battlement
	one of a series of rounded projections (or the notches between them) formed by curves along an edge (as the edge of a leaf or piece of cloth or the margin of a shell or a shriveled red blood cell observed in a hypertonic solution etc.)

battlement (verb)	crenel (verb)
	supply with battlements