hard core 
noun
1The most active, committed, or doctrinaire members of a group or movement: there is always a hard core of trusty stalwarts [as modifier]: a hard-core following...
- The Commission has reduced the fines imposed in the past where participants in cartels have played a reduced role in relation to the hard-core members.
- We know that most crime is committed by a hard-core group of repeat offenders.
- The Roman Catholics surprised everyone by electing a hard-core rightwinger as Pope.
Synonyms
diehard, staunch, dedicated, committed, steadfast, hard-line, dyed-in-the-wool, long-standing;
extreme, entrenched, radical, intransigent, uncompromising, rigid
informal deep-dyed
2 (usually hardcore) [mass noun] Popular music that is experimental in nature and typically characterized by high volume and aggressive presentation.And he's just got a nasty, hardcore, aggressive blues sound in his lead guitar playing....
- From dense post-modern electronica to hardcore techno, Planet Mu constantly surprises.
- I got a bunch of hardcore punk, ska and reggae playing guys and threw them the curve ball.
2.1Pornography of a very explicit kind: [as modifier]: hard-core porn...
- Earlier, the state had censored videos that showed cruel violence and hard-core pornography.
- Computers fed my addiction to hard work, creative planning and hard-core pornography.
- Reality TV plays on a tension similar to Bell's description of hard-core pornography.
3 [mass noun] British Broken bricks, rubble, or similar solid material used as a filling or foundation in building.
- over the hump
- over the long haul
- over the moon
- over the odds
- over there
- over-the-road
- over the sticks
- over the top
- over the transom
- over the wicket
- overthink
- overthought
- over-thoughtful
- overthrow
- overthrowable
- overthrowal
- overthrower
- overthrust
- overthwart
- overtilt
- overtime
- overtime ban
- over-timer
- overtime rate
- overtip