Jacket/ˈdʒækɪt/ Definition 1 of 4Pro Tip 1/3Seasonal Usage Different jackets are worn for weather changes; some are for warmth in winter. He grabbed his fleece jacket as the autumn air turned chilly. Pro Tip 2/3Fashion Item Jackets can be a style choice, like a leather jacket, which might not be for warmth. She wore a red leather jacket to add some flair to her outfit. Pro Tip 3/3Formal Attire A suit jacket is a part of formal clothing and usually matched with trousers. He wore a navy suit jacket to the job interview.