adjective (a)

• showing or representing unfavorably(adj.all)

  Example:
  An uncomplimentary dress.
  

  Synonym:
  unflattering
  Antonym:
  flattering
  

  source: wordnet30
• tending to (or intended to) detract or disparage(adj.all)

  Antonym:
  complimentary
  

  source: wordnet30