the.com/ell

means An old unit of length (roughly the distance from elbow to fingertip, later standardized to about 45 inches in England) once used mainly for measuring cloth.

from From Old English 'eln', going back to a very old Germanic and Indo-European root meaning 'forearm' or 'elbow' — the same ancient root that gives us 'elbow' and 'elbow-room,' and is distantly related to the Latin 'ulna.' The idea was simple and bodily: before standardized rulers, people measured fabric by the length of an arm, and the 'ell' was that arm turned into a trade standard — which is exactly why the proverb 'give him an inch and he'll take an ell' lands as a joke about greed scaled up to a whole limb's worth.