adjective (a)

• subjected to a physical (or chemical) treatment or action or agent(adj.all)

  Example:
  The sludge of treated sewage can be used as fertilizer.
  Treated timbers resist rot.
  Treated fabrics resist wrinkling.
  

  Antonym:
  untreated
  

  source: wordnet30
• given medical care or treatment(adj.all)

  Example:
  A treated cold is usually gone in 14 days; if left untreated it lasts two weeks.
  

  source: wordnet30
• made hard or flexible or resilient especially by heat treatment(adj.all)

  Synonym:
  hardened, tempered, toughened
  Antonym:
  unhardened, untempered
  

  source: wordnet30