adjective (a)

• boldly resisting authority or an opposing force(adj.all)

  Example:
  Brought up to be aggressive and defiant.
  A defiant attitude.
  

  Synonym:
  noncompliant
  Antonym:
  compliant
  

  source: wordnet30
• Full of defiance; bold; insolent; as, a defiant spirit or act.(adjective)

  source: webster1913