frock coat

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

• noun A man's dress coat or suit coat with knee-length skirts.

from The Century Dictionary.

• noun A body-coat, usually double-breasted and with a full skirt, worn by men: opposed to sack-coat, which has no skirt, and to cutaway, with short and tapering skirt. See coat, 2.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun A long double-breasted coat with long skirts, worn by men, now only on formal occasions.

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

• noun a man's coat having knee-length skirts front and back; worn in the 19th century