Definition from Wiktionary, the free dictionary
- (idiomatic) To be explosively angry; to lose one's temper.
- When my dad found out I had failed the exams, he just lost it.
- To begin to laugh uncontrollably.
- When the teacher's chair broke, the class completely lost it
- To lose one's mind, go crazy.
- To no longer have a skill or ability, to lose one's touch, to be washed up
- When you think about all she's done for the sport, it's kind of sad, but she's completely lost it over the past few years.
- (idiomatic) To lose control of a situation.