"No DEF" what does it mean?!

Hello! Back again for another episode of: "SparklishBobbin Learns Sims Community Vocabulary" lol Basically, I feel like I keep making these posts.

I've noticed the term "No DEF" being used in creators' profiles, and I have no idea what it means. I've seen it posted along side things like "No MODS" -which I do understand, but this one's escaping me.

I tried Googling it, but that has only resulted in Google thinking I mean the word "Node" instead of No DEF, or deciding to give me the definitions of "Sims/Sims 4" "Definition" or "Means/Meaning".... I have a lot of feelings about how Google's search engine works these days, but that's not important right now. 

I'm guessing that it's a gamer term of some kind but as The Sims is the only game I really play, and I'm not heavily involved with the community at large, things like this often go over my head. Honestly, I'm intensely socially awkward- even among the socially awkward, so places like Twitch, Reddit and Discord seem like weird and overwhelming corners of the internet to me. This message board is honestly the only place I've felt even remotely comfortable interacting... 

Wow this got rambley. Lots of words for one easy question... sorry about that lol 

But yes. If someone could please tell me what No DEF means, I would be very grateful. Thank you 🙂