The Free On-line Dictionary of Computing (30 December 2018):

word spamming

    Repeating a word many
   times in a web page, in a (usually futile) attempt to
   increase its relevance ranking in a search engine's index
   (to "spam" the index).

   "Repeating a word over and over in a Web page (known as word
   spamming) has no effect on the [page's] ranking [in the
   index]."  -- Altavista FAQ
   (http://altavista.digital.com/cgi-bin/query?pg=tmpl&v=faq.html).

   See also spamdex.

   (1997-04-09)