"Lost it" is a phrase that is commonly used to describe the loss of one's composure or self-control. However, there are several synonyms that can also be used to convey this meaning. One such synonym is "freaked out," which implies an extreme and often irrational reaction to a situation. Another synonym is "gone off the deep end," which suggests that someone has gone beyond the point of no return in terms of their emotional state. "Flipped out," "lost one's cool," and "had a meltdown" are also commonly used phrases that convey a similar meaning to "lost it." No matter which synonym you choose to use, they all effectively communicate the idea of someone losing their composure and control over their emotions.