Definition: Something that is surely not going to happen.
Sample usage: “Everyone’s saying we should go try that new live-squid restaurant, but I am definotely eating anything with moving tentacles.”
Popularity: On paper, it looks like a typo. The word on which it’s based — definitely — has the accent on the first syllable, and you can lean into it for effect: “I’m DEFinitely not.” Transferring the accent to the third syllable so you can swap out a vowel seems a bit high-concept. It sounds as if you’re mentioning the name of some obscure arty movie director. Aronofsky, Definotly. Whatever.
Chance of catching on: It’s trying too hard.