A sheath is a protective cover designed to hold a blade safely. Knights carried their swords in leather sheaths hung from their belts. Hunters slide their knives into sheaths to prevent accidents while hiking through the woods. A sheath keeps the sharp edge from cutting you or getting damaged, and it makes carrying the blade much safer and easier.

A sheath fits snugly around its blade like a glove fits a hand. Some sheaths are made of leather, others of wood, metal, or modern materials like nylon. Japanese samurai carried their katanas in beautiful lacquered sheaths called saya.

You might also hear about sheaths in nature: a leaf sheath wraps protectively around a plant's stem, just like a knife sheath wraps around a blade. Scientists use the word for protective coverings around nerves and other body structures.

The verb form is sheathe (with an 'e' at the end). When you sheathe your sword, you slide it back into its sheath. After a battle, a knight would sheathe his weapon to show the fighting had ended.