denim jacket       
noun [ C ] uk/ˌden.ɪm ˈdʒæk.ɪt/ us/ˌden.ɪm ˈdʒæk.ɪt/
 牛仔布外套,牛仔布夹克
a short coat made of denim (= a thick, strong cotton cloth, often blue, used especially for making jeans)
  Denim jackets never go out of style. 牛仔外套永远不会过时。 
 She wore a simple mauve T-shirt, a denim jacket and a pair of faded jeans. 她穿了一件简单的淡紫色T恤,一件牛仔夹克和一条褪色的牛仔裤。 
 Synonym: jean jacket
 - More examples
 - The black and red badge Marty wears on his denim jacket says "Art in Revolution".
 - A denim jacket will work with everything from your evening dress to skirts, trousers or even your sarong.
 - I tended to dress drably in black trousers, dark grey pullover and black denim jacket.
 - He's taken to dressing in young people's clothes. He wears denim jackets - with the collar up! - and sunglasses.