hard core

Universal Words noun (BrE) 1 [sing.+sing./pl.v.] the small central group in an organization, or in a particular group of people, who are the most active or who will not change their beliefs or behaviour: It's really only the hard core that bother(s) to go to meetings. * A hard core of drivers ignore the law. 2 [U] (usually hardcore) small pieces of stone, brick, etc. used as a base for building roads on