Yes, crenel is a Scrabble word!

Verb

1. Supply with battlements

Noun

1. 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.)

2. A notch or open space between two merlons in a crenelated battlement