(idiomatic) to keep one's cool; to keep a cool head

to lose one's cool; to lose one's head

(figuratively) to be chilling, to give the creeps, to send shivers down someone's spine

(figuratively) to blow hot and cold

(transitive with à) to leave (somebody) indifferent

(informal) not to be faint-hearted, not to be backward in coming forward, to have guts, to have plenty of nerves

revenge is a dish best served cold

feminine singular of froid

coldness, cold

once bitten, twice shy; a burnt child dreads the fire