Someone who hates losing; competitive and determined not to be beaten. Often hardworking and persistent, but can sometimes have trouble accepting defeat.
子どもの頃から負けず嫌いで、スポーツでは誰にも負けなかった。
I've been a sore loser since childhood and would never lose in sports.
彼女は負けず嫌いだから、毎日練習を欠かさない。
She's competitive, so she practices every day without fail.
負けず嫌いな性格は仕事で強みになることもあれば、協調性を損なうこともある。
A competitive nature can be an asset at work, but it can also harm teamwork.
試合で負けると悔しがる彼は、本当に負けず嫌いだ。
He gets upset when he loses in a match—he really hates losing.