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lose (one's) temper
To become angered, enraged, or upset due to some provocation; to have an outburst upon losing one's patience. I'm usually a pretty calm person, but whenever I start driving, I find I lose my temper at the slightest inconvenience. When we were kids, my dad lost his temper a lot, but he's mellowed out since then.
lose one's temper (at someone or something)
Fig. to become angry at someone or something. Lisa lost her temper and began shouting at Bob. I hate to lose my temper at someone. I always end up feeling guilty.