Furniture is the tables, beds and seats — all the big movable things that make a room usable. Everything you would have to hire a van for.
It is a mass noun with no plural, so you buy furniture, or a piece of furniture, and never two furnitures. The trap is that it does not include what is fixed, since a fitted kitchen is not furniture. English has a nice idiom for somebody so familiar they are no longer noticed, who becomes part of the furniture. Street furniture is a real term for benches, bins and lamp posts.
1nounfurnitureThe movable articles such as tables, chairs and beds that equip a room.
“They sold most of the furniture before moving.”
Furniture was the act of supplying before it was the chairs. Middle French fourniture meant a supply or a furnishing, from fournir, to furnish.
Middle French
fourniture — a supply, or the act of furnishing
English, today
furniture
Built from
From Middle French fourniture (“a supply, or the act of furnishing”), from fournir (“to furnish”).
Etymology from Wiktionary, CC BY-SA