ulna

Từ điển Oxford Advanced Learner 8th

ulna [ulna ulnae] BrE [ˈʌlnə] NAmE [ˈʌlnə] noun (pl. ulnaeBrE [ˈʌlniː] ; NAmE [ˈʌlniː] )(anatomy)
the longer bone of the two bones in the lower part of the arm between the elbow and the wrist, on the side opposite the thumb
see also ↑radius (³)

Word Origin:
late Middle English (denoting the humerus bone): from Latin; related to ↑ell.