Noun

1. A person who fails to win.

   In a two-horse race there is always one winner and one loser.

2. Someone who loses in a specified manner.

   He was always a good loser.

3. Someone with bad luck or poor skills who consistently loses.

   I’m a constant loser in love.

4. Something of poor quality.

   That dictionary is a loser!

5. A person of unhappy circumstances.

   That guy is a born loser!

6. A contemptible or unfashionable person.

   That person is a loser!

7. Someone that has lost weight. (a recent term, originally from Kelloggs, but now has come from NBC show "The Biggest Loser")

   She is such a loser, she lost 15 kilos!