crenel

(noun) 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.). Synonyms: scallop, crenation, crenature, crenelle.

(noun) a notch or open space between two merlons in a crenelated battlement. Synonyms: crenelle.

(verb) supply with battlements. Synonyms: crenelate, crenellate.