noun (n)

• a search for knowledge(noun.cognition)

  Synonym:
  enquiry, research
  

  source: wordnet30
• an instance of questioning(noun.communication)

  Synonym:
  enquiry, interrogation, query, question
  Antonym:
  answer
  

  source: wordnet30
• a systematic investigation of a matter of public interest(noun.act)

  Synonym:
  enquiry
  

  source: wordnet30
• The act of inquiring; a seeking for information by asking questions; interrogation; a question or questioning.(noun)

  source: webster1913