defeasance vs downthrow

defeasance

noun

  • The rendering void of a contract or deed; an annulment or abrogation. 

verb

  • To void; to annul. 

downthrow

noun

  • Ruin; defeat. 

  • A depression of the strata on one side of a fault 

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