Difference Between Ferrule and FeruleA ferrule is the circular metal ring or casing that is placed over the wooden tip of an umbrella or cane to prevent it from splitting on repeated contact with the ground. A ferule is a flat strip of wood, often marked off to serve as a ruler, used to punish schoolchildren; figuratively, it stands for schoolroom discipline. Both are pronounced FER-uhl, as is the adjective feral meaning “wild, untamed,” which is used particularly of domesticated animals that have reverted to the wild state.