hashtag vs trademark

hashtag

verb
  • To label (a message) with a hashtag. 

noun
  • A metadata tag, signaled by a preceding hash sign (#), used to label content. 

  • The hash sign itself, when used as part of a hashtag. 

trademark

verb
  • To so label a product. 

  • To register something as a trademark. 

adj
  • Distinctive, characteristic, signature. 

noun
  • Any proprietary business, product or service name. 

  • The aspect for which someone or something is best known; a hallmark or typical characteristic. 

  • A word, symbol, or phrase used to identify a particular company's product and differentiate it from other companies' products. 

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