hardcore
adj.adj. very intense, serious, or strict about something. You use this to describe people who are extremely dedicated to a hobby or style, or things that are very loud and fast.
adj. highly committed, intense, or uncompromising in nature. Often used to describe subcultures, musical genres with aggressive characteristics, or individuals who demonstrate extreme dedication to a specific activity.
He is a hardcore fan who never misses a game.
The band plays a hardcore style of punk music that is much faster and louder than typical rock.
While casual hikers stick to the marked trails, hardcore climbers often spend weeks preparing for the most dangerous vertical ascents in the mountain range.
From hard + core: hard to the core; 1936 (n.); 1951 (adj.)
Typically used before a noun to modify a person's level of commitment or the intensity of a genre.