mon·key·pox (m?ng?k?-p?ks?)n. An infectious disease caused by a poxvirus that occurs mostly in the tropical rain forests of central and western Africa, is transmitted from wild animals killed for food, such as monkeys and squirrels, and causes symptoms similar to but milder than smallpox.American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.