fanatic
nounUK /fəˈnæt.ɪk/
US /fəˈnæt̬.ɪk/
A fanatic is someone who likes something so much that they never stop talking about it.
My cousin is a football fanatic who watches every game.
OTHER MEANINGS
2. A person who is extremely and often unreasonably devoted to a cause or belief.
The rally attracted fanatics from across the country.
3. Used as an adjective to describe wildly enthusiastic or extreme behavior.
He has a fanatic love for old comic books.
4. Someone whose extreme devotion can make others uncomfortable or worried.
Her fanatic dedication to the diet worried her friends.