keep one’s cool
keep (one's) cool
To maintain control of one's composure, temper, or nerve in a given situation. He really kept his cool when the waiter dropped his food. I tried to keep my cool during the interview, but I was extremely nervous the whole time.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
keep one’s cool
tv. to remain calm and in control. (see also keep cool. Compare this with lose one’s cool.) It’s hard to keep your cool when you’ve been cheated.
McGraw-Hill's Dictionary of American Slang and Colloquial Expressions Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.