What is a "frock coat"?

A frock coat is a type of formal or semi-formal men's coat that was popular during the 19th and early 20th centuries. The coat is typically knee-length and features a fitted waist, full skirt, and wide lapels. Frock coats were commonly worn by wealthy or upper-class men for formal occasions such as weddings or balls, and were often made of luxurious materials such as silk or velvet. The style gradually fell out of fashion in the early 20th century but has experienced occasional revivals in modern times as a vintage or retro fashion item.