An ell (from Proto-Ino-European *el- "elbow, forearm"), when used as an English unit of length, is usually 45 inches, i.e. 1.143 m (for the international inch). It was mainly used in the tailoring business but is now obsolete. It was derived from the length of the arm from the shoulder (or the elbow) to the wrist, although the exact length was never defined in English law.