An antique chair is one of those objects that we all know is a chair (duh) and yet we have a hard time describing its component parts.
I know this isn't a real big deal but it does reduce a lot of us to "ooga-booga cave speak" that no client or vendor understands even though many of us are college graduates and some even Phi Beta Kappas (or Kappa Kappa Gammas which are just as good).
Anyhow, describing chairs and their parts is easily solved by reviewing the following diagrams that show what words apply to what parts of different antique chairs.
Here's a diagram of a French Regence armchair with notations as to all of its parts:
If you'd like more chair terminology (since different chair eras have different chair parts), memorize the following diagrams and you'll practically have a PHD in "Seating Technology". Let's start with an English Queen Anne armchair: