I’ve been trying to purchase a door for my kitchen, but terms keep popping up that I don’t understand.
What is a Cill please? (This option popped up under door accessories)
Cill is sill.
A windowsill (also written window sill or window-sill, and less frequently in British English, cill) is the horizontal structure or surface at the bottom of a window.
Or more generally, per a window and door manufacturer in the UK.
The oracle for the English language, the Oxford English Dictionary, lists cill as a variant spelling of sill. The book, A Dictionary of Architecture and Landscape Architecture uses cill exclusively as is common within our industry which is the spelling we’ll use throughout the article and our website. So, both spellings are correct although the most common usage is sill and not cill.