ardent
adj.adj. having very strong feelings of love, support, or loyalty for something. You use this to describe someone who is extremely enthusiastic about their beliefs or hobbies.
adj. characterised by intense emotion, passion, or devotion. Often describes supporters, fans, or believers who demonstrate unwavering commitment.
She is an ardent supporter of environmental protection.
The local team has a small but ardent group of fans who attend every single match, even in the rain.
His ardent pursuit of social justice led him to dedicate his entire career to legal reform, despite the significant personal and financial sacrifices required by such a path.
First attested circa 14th century as Middle English ardaunt, borrowed from Anglo-Norman ardent and Old French ardant, from Latin ardentem, accusative of ardēns, present participle of ardeō (“I burn”).
Typically used attributively before a noun like 'supporter', 'fan', or 'admirer'.