Impossible to Gauge

Impossible to Gauge is a reference to the "difficulty" of a monster when checked. All Notorious Monsters will show this difficulty when checked.

Meme

According to Square Enix, monsters that evoke fear in the hearts and minds of the players and inspire the peasants to pick up their pitchforks and slay in order to restore peace to society.

According to the playerbase, monsters that are slightly more difficult than an XP mob and have roughly the same drops.