English to English

verb (v)

• bring to a desired consistency, texture, or hardness by a process of gradually heating and cooling(verb.change)

  Synonym:
  normalize, temper
  

  source: wordnet30
• To subject to great heat, and then cool slowly, as glass, cast iron, steel, or other metal, for the purpose of rendering it less brittle; to temper; to toughen.(verb)

  source: webster1913