fanatic
n.someone who has extremely strong beliefs or interests that other people might find too much. You use this for people who are obsessed with a hobby or a religion.
n.a person motivated by excessive enthusiasm and often uncritical devotion, particularly regarding religious or political matters. In modern usage, it frequently describes someone with an intense interest in a specific hobby or pursuit.
“My brother is a real fitness fanatic who works out every day.”
“The movie star was followed everywhere by a group of fanatics who had waited hours just to see him.”
Often used with a modifying noun to specify the area of interest, such as 'sports fanatic' or 'health fanatic'.
“A self-described coffee fanatic, Sonis followed the lead of her husband Ethan, who launched an athletic training business in 2018.”
“He spent most of the coaching chapter of his life in Southeast Asia, where he heard about “a fanatic country in football” he is now leading into a new World Cup cycle.”
First attested in 1525. Learned borrowing from Latin fānāticus (“of a temple, divinely inspired, frenzied”), from fānum (“temple”). Influenced by French fanatique.
Etymology adapted from Wiktionary, available under CC BY-SA 4.0.