cubit
/ˈkjuːbɪt/noun
- an ancient measure of length, approximately equal to the length of a forearm. It was typically about 18 inches or 44 cm, though there was a long cubit of about 21 inches or 52 cm.肘尺（一种古代长度单位, 大约相当于前臂的长度, 常为约18英寸或44厘米, 长肘尺约为21英寸或52厘米）。
词源
Middle English: from Latin cubitum 'elbow, forearm, cubit'.