noun (n)

• the act of inhaling; the drawing in of air (or other gases) as in breathing(noun.act)

  Synonym:
  aspiration, breathing in, inspiration, intake
  

  source: wordnet30
• a medication to be taken by inhaling it(noun.artifact)

  Synonym:
  inhalant
  

  source: wordnet30
• The act of inhaling; also, that which is inhaled.(noun)

  source: webster1913