A shell jacket is a lightweight outer layer that often features a waterproof or water-resistant membrane. It's commonly worn as a top layer to keep the wearer dry and protected from wind during outdoor activities like hiking, camping, and skiing. Synonyms for shell jacket include windbreaker, rain jacket, waterproof jacket, parka, and anorak. A windbreaker is designed to shield the wearer from wind, while a rain jacket is specifically designed to repel water. A waterproof jacket is similar to a rain jacket but made from more durable materials and often includes additional features like breathable fabrics or sealed seams. A parka is a longer, insulated shell jacket that's designed for colder temperatures, while an anorak is a pullover-style shell jacket that often includes a hood.