'tailcoat' originates from English, specifically a compound of 'tail' and 'coat', where 'tail' originally referred to the hanging part or 'rear piece' of a garment and 'coat' meant 'an outer garment'.

'tailcoat' developed from phrases like 'tailed coat' (used in the 18th century to describe coats with tails) and by the 19th century became established as the single-word 'tailcoat' referring particularly to formal evening dress.

Initially it referred broadly to any coat with a tail or tails (including riding or coachmen's coats); over time it became specialized to mean the formal evening dress coat worn with white tie.