Dictionary

Frock coat is a formal men’s coat, fitted and long-sleeved, with a centre vent at the back, buttoned down to the waist. Frock coat usually had a suit-like collar and lapels

Originally frock coats were called “redingotes”, derived from a French alteration of the English “riding coat”. Frock coats first appeared in the XVIII century and continue to be a fashion item in modern menswear.