a lightweight jacket that looks like part of a suit but is less formal, often worn as part of a school or club uniform or paired with casual trousers
He slipped on a navy blazer before heading out to dinner.
The students’ green blazers all had the school crest sewn onto the breast pocket.
✦ Early 19th-century: originally referring to the red jackets worn by members of the Lady Margaret Boat Club at Cambridge University, from blaze (bright flame or color) + ‑er.
