hard core

noun
1.
the permanent, dedicated, and completely faithful nucleus of a group or movement, as of a political party.
2.
an unyielding or intransigent element in a social or organizational structure, as that part of a group consisting of longtime adherents or those resistant to change.
3.
those whose condition seems to be without hope of remedy or change.
Origin
1935-40

hard-core

[hahrd-kawr, -kohr] /ˈhɑrdˈkɔr, -ˈkoʊr/
adjective
1.
unswervingly committed; uncompromising; dedicated:
a hard-core segregationist.
2.
pruriently explicit; graphically depicted:
hard-core pornography.
Compare soft-core.
3.
being so without apparent change or remedy; chronic:
hard-core inflation; hard-core unemployment.
Origin
1950-55
British Dictionary definitions for hard core

hard core

noun
1.
the members of a group or movement who form an intransigent nucleus resisting change
2.
material, such as broken bricks, stones, etc, used to form a foundation for a road, paving, building, etc
adjective
3.
(of pornography) describing or depicting sexual acts in explicit detail
4.
extremely committed or fanatical: a hard-core Communist
Slang definitions & phrases for hard core

hard-core

adjective

Essential and uncompromising; unmitigated: a hard-core Republican/ hard-core pornography (1951+)

noun

Pornography that openly depicts complete sex acts: He sort of likes dirty stuff, but not real hard core (1970s+)