cills
Cills are the bottom horizontal members of window openings, and in some dialects the spelling cill is used instead of sill. The plural form cills refers to more than one such element. In modern usage the term is often interchangeable with sill or windowsill, but cill is more commonly found in historical or regional texts, particularly in Scotland and parts of northern England.
Exterior cills are part of the window assembly and may project beyond the wall to shed rainwater
Construction and maintenance considerations focus on moisture control and structural integrity. Proper flashing and weatherproofing are
Etymology and usage notes: the spelling cill is chiefly found in British English and Scottish sources, while