helpmate vs subalternate

helpmate

noun
  • A recreational problem in chess in which both sides cooperate to achieve a specific goal. 

  • A person who supplies help or companionship. 

  • A wife or spouse. 

subalternate

noun
  • A particular proposition, as opposed to a universal one. 

adj
  • Succeeding by turns; successive. 

  • Subaltern; inferior; subordinate. 

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