Definitions
1.NounA person who loses; one who fails to win or thrive."In a two-horse race there is always one winner and one loser.; He was always a good loser."
2.NounSomething of poor quality.
3.NounA person who is frequently unsuccessful in life."That guy is a born loser!; I'm a constant loser in love."
4.NounA contemptible or unfashionable person.
5.NounOne who or that which loses something, such as extra weight, car keys, etc.
6.NounA losing proposition, one that is likely to lose or already has lost (such as a losing bet or, analogously, a predictably fruitless task or errand).
7.NounA person convicted of a crime, especially more than once."He's a three-time loser doing twenty years."