Real Dictionary

cool down
phrasal verb: If someone cools down or if you cool them down, they become less angry than they were.

cool down in American English
the act or an instance of gradually slowing or cooling down after vigorous exercise
to bring the body back to its normal physiological level after fast, vigorous exercise or activity by gradually slowing the pace of activity or by doing gentle exercises or stretches
to lower the body temperature, pulse, etc. after vigorous exercise