25B6; adjective DIEHARD, staunch, dedicated, committed, steadfast, dyed-in-the-wool, long-standing; hard-line, extreme, entrenched, radical, intransigent, uncompromising, rigid; informal deep-dyed.
HARD-CORE
Meaning of HARD-CORE in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012