killfile

/K IH1 L F AY0 L/
noun
  1. 1

    A user's file listing the users of a newsgroup whose postings are to be ignored, or other criteria for ignoring posts.

verb
  1. 1

    To add (a user) to a kill file.

Source: https://en.wiktionary.org/wiki/kill%20file, https://en.wiktionary.org/wiki/killfile