noun (n)

• a sentence of inquiry that asks for a reply(noun.communication)

  Example:
  He had trouble phrasing his interrogations.
  

  Synonym:
  interrogative, interrogative sentence, question
  

  source: wordnet30
• a transmission that will trigger an answering transmission from a transponder(noun.communication)

  source: wordnet30
• formal systematic questioning(noun.communication)

  Synonym:
  examination, interrogatory
  

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

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

  source: wordnet30
• The act of interrogating or questioning; examination by questions; inquiry.(noun)

  source: webster1913