From Longman Dictionary of Contemporary Englishtailcoattail‧coat /ˈteɪlkəʊt $ -koʊt/ noun [countable] DCCa man’s jacket which is short at the front and divided into two long pieces at the back, worn to very formal events SYN tails
Examples from the Corpus
tailcoat• He had a distinguished air, was formally dressed in a tailcoat, and was precisely my idea of an ambassador.• On board days he would wear a tailcoat.• He had shoulder-length, gleaming black ringlets of hair, a pointy beard, and wore a tailcoat.• Gerald had asked his tailor to sew little loops into his tailcoat so that the Order did not have to be continually readjusted.• His tailcoat, his white tie, his dancing pumps, all impeccable.• No fancy dress for him; he even felt uncomfortable in his faithful old tailcoat and old-fashioned collared waistcoat.• Holding up her light, Anne saw a cavernous opera cape with a Mephistophelean magician's tailcoat hanging inside it. 