'Chair' was mentioned in an earlier post. I got stuck on that word and can't help thinking about it.

Chair means chair? What is that? Is it the sexless leader at a meeting? What the leader of a meeting does? A leading position (Sir James Chair of Physics, the Chair of the diocese, etc.? The support of a rail or other construction piece?

Did it once mean something to sit on? 'Tis a puzzlement.