noun (n)

• (chemistry) the process of refinement or purification of a substance by distillation(noun.process)

  source: wordnet30
• the conversion of alternating current to direct current(noun.event)

  source: wordnet30
• the act of offering an improvement to replace a mistake; setting right(noun.act)

  Synonym:
  correction
  

  source: wordnet30
• determination of the length of a curve; finding a straight line equal in length to a given curve(noun.act)

  source: wordnet30
• The act or operation of rectifying; as, the rectification of an error; the rectification of spirits.(noun)

  source: webster1913