Définition et Signification de "[lose] {one's} cool"

What is the origin of the idiom "lose one's cool" and when to use it?

The origin of the idiom "lose one's cool" can be traced to American English slang from the mid-20th century. The term "cool" in this context refers to maintaining a calm, composed, and unruffled demeanor. It can be employed in personal relationships during arguments or conflicts when individuals become overwhelmed by their emotions and react impulsively. In professional settings, it may be used to describe moments of high stress or pressure, such as during presentations, meetings, or negotiations, when someone becomes visibly flustered or unable to maintain a calm demeanor.