overgeneralization

over- +‎ generalization

overgeneralization (countable and uncountable, plural overgeneralizations)

1. (usually uncountable) The act of overgeneralizing.
   • 1995 July 7, Gary Houston, “Everything's Unique”, in Chicago Reader‎:

     "George Orwell put the easy use of words like 'unique' under the headings of 'pretentious diction' and overgeneralization.

   • 1988 November 11, Andrew Goodwin, “Reading: The Cultural Crash of '89”, in Chicago Reader‎:

     Fortunately for all of us, the rhetoric of both cultural pessimism and postmodernism contains more than its fair share of exaggeration and overgeneralization.

2. (countable) An instance of overgeneralizing.
   • 2000 January 28, Keith Kloor, “RESTORATION ECOLOGY:Returning America's Forests to Their 'Natural' Roots”, in Science‎, volume 287, number 5453, →DOI, pages 573–575:

     It's an overgeneralization to say that everywhere you look is the hand of man in the presettlement era," says Thomas Swetnam, a fire ecologist at the University of Arizona in Tucson.