arch·duke (ärch-dk, -dyk)
1. In certain royal families, especially that of imperial Austria, a nobleman having a rank equivalent to that of a sovereign prince.
2. Used as a title for such a nobleman.
[Obsolete French archeduc : arche-, arch- (from Old French; see ARCH-1) + duc, duke (from Old French; see DUKE).]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2022 by HarperCollins Publishers. All rights reserved.
Indo-European & Semitic Roots Appendices
Thousands of entries in the dictionary include etymologies that trace their origins back to reconstructed proto-languages. You can obtain more information about these forms in our online appendices:
The Indo-European appendix covers nearly half of the Indo-European roots that have left their mark on English words. A more complete treatment of Indo-European roots and the English words derived from them is available in our Dictionary of Indo-European Roots.