junk mail vs spam

junk mail

noun
  • Any mail or letters that are not welcome or solicited and typically sent in bulk; especially mail of a commercial nature such as advertising circulars and form letters. 

spam

noun
  • Unsolicited bulk electronic messages. 

  • A type of tinned meat made mainly from ham. 

  • Any undesired electronic content automatically generated for commercial purposes. 

verb
  • To send spam (i.e. unsolicited electronic messages) to a person or entity. 

  • To post the same text repeatedly with disruptive effect; to flood. 

  • To do something rapidly and repeatedly. 

  • To send spam (i.e. unsolicited electronic messages.) 

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