1 to stop having something that you had before -- ~を失う
2 to have less of something than you had before -- ~を減らす
3 If you lose a game, the team or person that you are playing against wins. -- (試合などに)負ける
Chelsea lost by a goal.
They’re losing 3–1.
4 to waste something such as time or an opportunity -- (機会、時間など)を無駄にする
6 to become crazy -- 気が動転する, 頭がおかしくなる