box coat

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A coat designed to hang loosely from the shoulders.
• noun A heavy overcoat formerly worn by coachmen.

from The Century Dictionary.

• noun A heavy overcoat worn by coachmen.
• noun Early in the present century, an overcoat with a cape, approximately of the form of the coachman's great-coat: intended originally for travelers on the outside of coaches.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a short coat that hangs loosely from the shoulders