How is it really spelled?

The correct spelling is - Fir wood, furring strips, soffit. Also overhangs of roofs are also called soffits. I found different parts of the country call the same things different names and in different countries. It took me a while to figure out a lounge was a living room in Europe not a bath room.

Fir is a type of tree. Furring strips are building material. Fur down is a bizarre term and strangely incorrect for the space above a kitchen cabinet and the ceiling.

I think I now see what project you were talking about. I too have never heard of "fur down", never, doesn't even make sence. The bloggers were from Texas, but I think thier contactor friend was pulling their leg.

In the South USA, an interior ceiling soffit is commonly called a fur-down.

I agree, it is a regional term.

Yes, we Texans do call the furred down ceiling above kitchen cabinets a fur-down. Seems pretty reasonable to us. Not sure of the spelling though. On line Webster’s doesn’t like any of ‘em.

Furring strips are the thin strips of wood that can be used for all sorts of things such as leveling up a wall. You're correct about a soffit but it's also used in other places other than above cabinets and typically hides things like ductwork or electrical. Fir is a type of tree, so you've pretty well got it right there!

"Fir" is a type of tree, where as "Fur" is the stuff that covers animals!

There are fir trees and sometimes the wood is used for construction. In checking/researching it seems that in the UK the term for strips of wood used in construction are called firring trips and spelled as such. In America the spelling is furring....so basically either is appropriate.