someone who is in a worse situation than they were, because of something that has happened [≠ winner]:
If the strike continues, the people of Galway will be the real losers.
someone who is never successful in life, work, or relationships:
What a loser!
The guy's a born loser.
someone who has lost a competition, game, election etc [≠ winner]
good/bad loser (=someone who behaves well or badly after losing)