(idiomatic) To become upset or disconcerted; to lose one's temper.

(idiomatic) To remain composed, calm, and even-tempered, especially in a provocative situation.

(idiomatic) To keep one's cool; to stay calm.

(idiomatic) To wait, especially impatiently or restlessly.

(Internet slang, colloquial) Used to dismiss a comment perceived as boring or pointless, or refute an anecdote that one considers difficult to believe.

present participle of lose one's cool

simple past tense and past participle of lose one's cool

Third-person singular simple present indicative form of lose one's cool

Alternative form of cooler heads will prevail

Alternative form of cooler heads will prevail