The Free On-line Dictionary of Computing (19 January 2023):

newsfroup

    A silly synonym for Usenet newsgroup,
   originally a typo but now in regular use on Usenet's
   news:talk.bizarre and other lunatic-fringe groups.

   Compare hing, grilf, and filk.

   [Jargon File]

   (1994-12-13)


The Jargon File (version 4.4.7, 29 Dec 2003):

newsfroup
 //, n.

    [Usenet] Silly synonym for newsgroup, originally a typo but now in
    regular use on Usenet's talk.bizarre, and other lunatic-fringe groups.
    Compare hing, grilf, pr0n and filk.