Definition of "cool-headed" [cool•-head•ed]

• Not easily excited or flustered. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "Oscar is described as the cool-headed but ruthless younger brother of Chicago Mafia boss Bruno Bianchi, who was murdered in the first episode during an altercation with Bunny Maureen Amber Heard."
• "On a case, he needs to be cool-headed to the point of being a machine."
• "Among the many retorts, perhaps the most carefully argued and cool-headed came from Ben Brandzel and his all-star co-authors, Tate Hausman, Paul Adler and Ben Wikler."