The words used to describe the large soft piece of furniture on which more than one person can sit at a time are a SECRET CODE designed to inform the listener about the educational background of the speaker. It works like this:

The thing = high school dropout

Davenport (or Daveno) = high school graduate

Couch = community college graduate

Sofa = B.A. from a state college or university

Settee = one of those Eastern colleges which admitted only women.

Chesterfield = Ivy League degree or pretensions to one