the.com/battlements
The castle's gap-toothed grin, designed so archers could shoot and still take cover.
means The notched parapet along a castle wall, alternating solid blocks and open gaps for defense.
from From Old French batailler, to fortify, via batail, battle — literally the wall built for fighting from.
Proper termsSolid bits are merlons, gaps are crenels.
Status symbolLater added purely for prestige, no defense intended.
Royal permitEngland required a license to crenellate your home.