Noun loser has 3 senses
  1. loser, also-ran - a contestant who loses the contest
    --1 is a kind of contestant
    Antonyms: winner, victor
    Derived form: verb lose2
  2. failure, loser, nonstarter, unsuccessful person - a person with a record of failing; someone who loses consistently
    --2 is a kind of unfortunate, unfortunate person
    Antonyms: achiever, winner, success, succeeder
    --2 has particulars:
     bankrupt, insolvent; flash in the pan; flop, dud, washout; underdog
    Derived form: verb lose2
  3. loser - a gambler who loses a bet
    --3 is a kind of
    Antonyms: winner
    Derived forms: verb lose7, verb lose2