There are various synonyms for the word "shell" that can be used to describe an outer covering, such as casing, husk, carapace, exoskeleton, or sheath. These words can be used to describe different types of coverings, from the protective covering of a turtle's shell or crab's exoskeleton to the hard outer layer of an egg or nut. In addition, the word can also refer to a projectile's casing or a military weapon's ammunition container. Therefore, depending on the context, using a synonym for the word shell can add clarity and precision to any written or spoken communication.