Verb (5-dan, す, transitive)
1. to cool; to chill; to refrigerate
ちゃんと冷やさなくて大丈夫？Is it okay if you don't chill it properly?
2. to calm down; to cool off; to regain one's composure; to relax
こんな状況だけど、頭冷やしてちゃんとお仕事しようか。Even in this situation, let's calm down and do our work properly.
3. to be frightened (at); to be scared (of)