noun (n)

• an inquiry into unfamiliar or questionable activities(noun.cognition)

  Synonym:
  probe
  

  source: wordnet30
• the work of inquiring into something thoroughly and systematically(noun.act)

  Synonym:
  investigating
  

  source: wordnet30
• The act of investigating; the process of inquiring into or following up; research; study; inquiry, esp. patient or thorough inquiry or examination; as, the investigations of the philosopher and the mathematician; the investigations of the judge, the moralist.(noun)

  source: webster1913