1. The outermost layer of insulation
on a multi-conductor
cord or cable. This both serves as protection for the inner conductors and as a method of keeping them bound together. Also known as the sheath
2. Article of clothing. A medium or light weight outer wear. Usually worn over one's shirt (and vest if one is worn). May be formal such as a suit jacket or tux coat, decorative such as a leather western fringe jacket, uniform as a biker gang leather jacket or a military jacket or as utilitarian as a down jacket for cold weather wear.