Cubit -- An ancient unit of linear measure, about 18-22 inches; orig., the length of the arm from the end of the middle finger to the elbow (Webster's New World College Dictionary)
For only Og King of Bashan remained of the remnant of giants; behold, his bedstead was a bedstead of iron ... nine cubits was the length thereof, and four cubits the breath of it, after the cubit of a man.