archduke

詳細解釋：

arch.duke

n.（名詞）
In certain royal families, especially that of imperial Austria, a nobleman having a rank equivalent to that of a sovereign prince.
大公：在某些皇族尤指奧地利帝國中，具有與有主權的王子相等地位的貴族
Used as a title for such a nobleman.
大公：用作這樣一個貴族的封號

來源：
Obsolete French archeduc
已廢法文 archeduc
arche- [arch-]
arche- [前綴，表.主要的.]
duc [duke] * see duke
duc [公爵] *參見 duke