sports jacket 
(US also sport jacket or sports coat)
noun
A man’s jacket resembling a suit jacket, for informal wear.To make your upper body look more muscular, wear small shoulder pads in your blazers, jackets and sports jackets....
- The Huntsman collection includes suits, sports coats, overcoats, blazers, shirts and ties: time-honoured essentials of the smartly-attired gentleman about town and country.
- In addition to actual jean jackets, denim sports jackets are also all the rage in fashionable circles.