To lose heat, to get colder.
I like to let my tea cool before drinking it so I don't burn my tongue.
To make cooler, less warm.
To become less intense, e.g. less amicable or passionate.
Relations cooled between the USA and the USSR after 1980.
To make less intense, e.g. less amicable or passionate.
To kill.
Brought to a lower temperature.
Brought to a lower temperature by means of (often in compounds).
a water-cooled engine
Brought to a reduced degree of anger or fervour.