Fromoffensive +‎-ness.

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offensiveness (countable anduncountable,pluraloffensivenesses)

1. The quality of beingoffensive.
   • 2011 September 21, Erica Ho, “Poll Finds Young People Aren’t Bothered by Slurs Used Online”, inTime‎^[1]:

     Some slurs like “slut” and “retard” vary in their perceivedoffensiveness to those polled, but also include some incredibly offensive words like the “N-word.”