backslash vs knock

backslash

noun
  • Used erroneously in reference to, or in reading out, the ordinary slash, that is, the punctuation mark /. 

  • The punctuation mark \. 

  • |passage= […] I was trying to find a web-site for which I had been given the following address: http://www.isop.ucla.edu/pacrim/pubs/korjournal.htm. […] I began to work backwards, removing first the last part of the address following the last backslash (/korjournal.htm).}} 

verb
  • To escape (a metacharacter) by prepending a backslash that serves as an escape character, thereby forming an escape sequence. 

knock

noun
  • A criticism. 

  • An abrupt rapping sound, as from an impact of a hard object against wood. 

  • A sharp impact. 

  • A batsman's innings. 

  • A blow or setback. 

  • Preignition, a type of abnormal combustion occurring in spark ignition engines caused by self-ignition; also, the characteristic knocking sound associated with it. 

  • Synonym of hunger knock 

verb
  • To criticize verbally; to denigrate; to undervalue. 

  • To kick a ball towards another player; to pass. 

  • To rap one's knuckles against something, especially wood. 

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