insinuation vs secret message

insinuation

noun
  • That which is insinuated; a hint; a suggestion, innuendo or intimation by distant allusion 

  • The act or process of insinuating; a creeping, winding, or flowing in. 

  • The act of gaining favor, affection, or influence, by gentle or artful means; — formerly used in a good sense, as of friendly influence or interposition. 

  • The art or power of gaining good will by a prepossessing manner. 

secret message

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