embargo vs knock-back

embargo

noun
  • A heavy burden or severe constraint on action or expenditure. 

  • A temporary ban on making certain information public. 

  • An order by the government prohibiting ships from leaving port. 

  • A ban on trade with another country. 

verb
  • To impose an embargo on trading certain goods with another country. 

  • To impose an embargo on a document. 

knock-back

How often have the words embargo and knock-back occurred in a corpus of books? (source: Google Ngram Viewer )