What is the definition of a "stuff" in (Fantasy points) pro football?

In my FF league one setting is receiving 1 defensive point for a "stuff". I was ahead by 3 points after all the games in Week 17 and when I checked the score this AM, 4 points had been added to my opponents defense (Pittsburgh Steelers). This placed him 1 point ahead of me for 3rd place... so now I'm am in 4th place... he is also the league commissioner. Trying to figure out how he acquired 4 additional points overnight. The only points I can not account for are "stuffs" from Pittsburgh's defense... any ideas?