1. The male ruler of an empire.
2. 1. The emperor butterfly.
   2. The emperor moth.

[Middle English emperour, from Old French empereor, from Latin imperātor, from imperāre, to command : in-, in; see en-¹ + parāre, to prepare.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.