Also, keep a cool head; stay cool; be cool; (take it cool). Remain calm and under control, as in Keep cool, they'll soon show up, or Be cool, the surprise is not spoiled, or You have to keep a cool head in these volatile situations, or Sit tight, take it cool, they won't bother you again. All these terms employ cool in the sense of “not heated by strong emotion,” a usage dating from the late 1300s or even earlier. The first three expressions are colloquial and date from the second half of the 1800s; both of the last two are slang, and the very last (take it cool) is the oldest, first recorded in 1841. Also see keep one's cool; play it cool.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use keep cool in a sentence
Power grids have struggled to put out enough electricity as overheated Americans try to keep cool both at home and at work.EnerNOC Helps Keeps Lights on During Heat Waves Through Demand Response | Edward Ferguson | July 20, 2013 | THE DAILY BEAST
Gardner surmised that during the day LaFever may have stayed in the river to keep cool, which slowed his rate of dehydration.Ray Gardner Used Autism Training To Find William LaFever | Laura Colarusso | July 14, 2012 | THE DAILY BEAST
"keep cool, Wes," MacHenery whispered to his opponent as they dos-à-doed back into position.The Great Potlatch Riots | Allen Kim Lang
The governor of Charleston having sent word to the general, "keep cool and do mischief," the fire was promptly returned.The Story of the Thirteen Colonies | H. A. (Hlne Adeline) Guerber
He tried to restrain what he wanted to say to that—keep cool, wise, and say the things that would get Edith.Fidelity | Susan Glaspell
Remember, daughter,” he declared, “I rely on you and Bab to keep cool heads and clear brains in any emergency.The Automobile Girls in the Berkshires | Laura Dent Crane
It is then spread in little heaps on the floor or trays, having to be constantly turned over to keep cool.