1. The male ruler of an empire.
a. The emperor butterfly.
b. The emperor moth.
c. The emperor penguin.
[Middle English emperour, from Old French empereor, from Latin imperātor, from imperāre, to command : in-, in; see EN-1 + parāre, to prepare; see perə-1 in the Appendix of Indo-European roots.]
The American Heritage® Dictionary of the English Language, Fifth Edition copyright ©2018 by Houghton Mifflin Harcourt Publishing Company. 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.