IPA: /fəˈnætɪkəlnəs/
KK: /fəˈnætɪkəlnəs/
The quality of being extremely enthusiastic or devoted to a particular cause or belief, often to an excessive or extreme degree.
His fanaticalness about the team made him attend every game, no matter the distance.
Fanaticalness → It is formed from "fanatic" (from Latin *fanaticus*, meaning inspired by a deity or possessed by a god) and "-al" (meaning pertaining to) and "-ness" (meaning the state of being). The word "fanaticalness" refers to the state of being excessively enthusiastic or zealous, often to an extreme degree.
Think of being 'inspired by a deity' ('fanaticus') and how that leads to a state of being overly enthusiastic or zealous.