noun
Refers to a person who has lost in competition, life, or social standing. Often carries a pitiful or contemptuous nuance, like a 'beaten dog'. Can also be used for someone who is habitually unsuccessful.
彼は選挙に落ちて、すっかり負け犬のようだ。
After losing the election, he looks completely like a loser.
Throw away that loser mentality and try again.
noun
unmarried and childless older woman
Slang, derogatory. Popularized by the book '負け犬の遠吠え' (The Howl of the Loser Dog). Refers to an unmarried, childless woman over 30, implying she has 'lost' in the societal game of marriage and family.
See also: お一人様 (おひとりさま)
「負け犬」という言葉は、未婚の女性に対する差別的なレッテルとして批判されることもある。
The term 'makeinu' is sometimes criticized as a discriminatory label against unmarried women.