proposal vs supposal

proposal

noun
  • A scheme or design 

  • The terms or conditions proposed 

  • The document on which such a thing is written. 

  • The offer by a party of what he has in view as to an intended business transaction, which, with acceptance, constitutes a contract. 

  • The act of asking someone to be one's spouse; an offer of marriage 

supposal

noun
  • Something supposed; a supposition, a hypothesis. 

  • The act of supposing; supposition. 

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