to not win, or to fail at something, normally in sports or athletics.
If you mean to your friends, you will lose friends and they will also be mean to you.
To lose your excitement
To lose
Lose is the opposite of win. If someone says "you lose," they mean you didn't win.
To falter can mean to lose momentum if you falter while striving towards an end goal. But you could also falter as in lose strength.
Find the KGB & lose the BREWHA...
to lose one's nerve - to take fright, to panic
to lose your job.
If you mean lose it on your computer, then I would recommend re-downloading it.
You are said to lose your shirt when you gamble everything you have and lose.
If you mean the weapons you've unlocked with skill points, then you lose them when you re-spec your character or enter veteran mode. If you mean in battle you can lose your main weapon by picking up an enemies weapon but you'll lose that when you die.
Crying when you lose a game.