enquiring vs interrogation

enquiring

noun
  • An instance of making an enquiry; an asking. 

adj
  • Curious, inquisitive or investigative. 

interrogation

noun
  • The act of interrogating or questioning; examination by questions; inquiry. 

  • A question put; an inquiry. 

How often have the words enquiring and interrogation occurred in a corpus of books? (source: Google Ngram Viewer )