below the belt

• (UK) IPA^(key): /bɪˈləʊ ðiː bɛlt/
• (US) IPA^(key): /bəˈloʊ ðə bɛlt/

• Audio (General Australian):

  (file)

below the belt

1. (boxing) Of a punch, landing illegally, below the opponent's waist.
2. (by extension, idiomatic) Unfair; dirty; not according to the generally accepted rules.

   Commenting on his bachelorhood in a debate on marital ethics was a bit below the belt, don't you think?

• hit below the belt, most common verb form

• low blow
• under one's belt