box coat

American Heritage® Dictionary of the English Language, Fourth Edition

1. n. A coat designed to hang loosely from the shoulders.
2. n. A heavy overcoat formerly worn by coachmen.

Century Dictionary and Cyclopedia

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

GNU Webster's 1913

1. n. a thick overcoat for driving; sometimes with a heavy cape to carry off the rain.

WordNet 3.0

1. n. a short coat that hangs loosely from the shoulders