parlance vs underword

parlance

noun
  • A certain way of speaking, of using words; especially that associated with a particular job or interest. 

  • Of a word, the quality of being lexicalized; especially as jargon or slang. 

underword

noun
  • A word placed below another, either literally or metaphorically: a subtext; an inadequate or subordinate term or description; a secret word or phrase; a watchword 

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