announcement vs prospectus

announcement

noun
  • That which conveys what is announced. 

  • An act of announcing, or giving notice. 

  • The content which is announced. 

prospectus

noun
  • A document, distributed to prospective members, investors, buyers, or participants, which describes an institution (such as a university), a publication, or a business and what it has to offer. 

  • A booklet or other document giving details of a share offer for the benefit of investors. 

  • A document which describes a proposed endeavor (venture, undertaking), such as a literary work (which one proposes to write). 

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