What about stools? I don't consider a stool to be a chair, I consider them two subtypes of seating. If someone told me to grab a chair and gestured to a stool I'd find it very slightly odd.
Fine
To sit an individual at close to, or at, a right angle in regards to their legs
A small rock versus a big rock; Approximating a squat, or standing, is out of bounds
But a stool may consistute a chair when sitting a child
Regardless, I'm mainly talking about the approach to defining it, and that definition by purpose rather than structure is more likely to find a correct definition, not that my example definition is sufficient
> a chair is any object whose primary purpose is to sit a single individual
So is a zabuton[1] a chair?
what if we add: "with one's feet firmly on the ground and legs bent at knee at more or less right angle?"
Eg, a chair is any object whose primary purpose is to sit a single individual
If it's meant to seat multiple people, it's a bench, a sofa, etc, but not a chair
If it's meant to be extra comfortable, it might be a single-seat sofa, but this itself a chair
If it's a rock, but positioned such that it's primary purpose is to sit an individual, such as next to a table, then it's a chair.
And most notably, primary purpose is subjective -- it might be understood as a chair, or as a doorstop, depending on your viewpoint, and what you use it for.