hit man or hit·man (h?t?m?n?)n. Slang 1. A hired murderer, especially one who is in the pay of a crime syndicate.2. A hatchet man.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.