Smart casual is an ambiguously defined Western dress code that is generally regarded as casual wear but with smart (in the sense of "well dressed") components from conventional informal wear in a proper lounge suit.
Usually, this definition includes dress shirt, tie, pants and dress shoes, but instead it is paired with an unusual blazer or a sports coat.
Smart casual originated in the 20th century as a dress code, originally
designating a lounge suit of unusual color and less heavy and therefore more casual material, with probably more casual cut and details. As the one-colored lounge suit came to define informal wear, smart casual was associated with uneven colors.
