The term 'OLD UNIT OF LENGTH' can be summarized as the ELL, which is a three-letter unit of length used in the past. It was a unit of measurement used in the English system of weights and measures, and was equal to one-tenth of a yard. The ELL was also used in the Scottish system of weights and measures, and was equal to 45 inches. The ELL was eventually replaced by the metric system in the 19th century.