blacken vs tar

blacken

verb
  • To defame or sully. 

  • To make dirty. 

  • To cook (meat or fish) by coating with pepper, etc., and quickly searing in a hot pan. 

  • To become black. 

  • To cause to be or become black. 

tar

verb
  • To besmirch. 

  • To create a tar archive. 

  • To coat with tar. 

noun
  • A file produced by such a program. 

  • A black, oily, sticky, viscous substance, consisting mainly of hydrocarbons derived from organic materials such as wood, peat, or coal. 

  • A Persian long-necked, waisted string instrument, shared by many cultures and countries in the Middle East and the Caucasus. 

  • A solid residual byproduct of tobacco smoke. 

  • A single-headed round frame drum originating in North Africa and the Middle East. 

  • Black tar, a form of heroin. 

  • Coal tar. 

  • A program for archiving files, common on Unix systems. 

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