crenel vs crenellation

crenel and crenellation both are nouns.

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

crenel (noun)	crenellation (noun)
a notch or open space between two merlons in a crenelated battlement	the action of constructing ramparts with gaps for firing guns or arrows
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.)	a rampart built around the top of a castle with regular gaps for firing arrows or guns

crenel (verb)	crenellation (verb)
supply with battlements