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.
The American Heritage Dictionary Blog
Check out our blog, updated regularly, for new words and revised definitions, interesting images from the 5th edition, discussions of usage, and more.