1) Something generally regarded as hardcore, except having fallen into obsolesence, or dispopularity.
2) As a replacement of hardcore when the subject is old.
1) I only listen to oldcore Metal. The new stuff sucks.
2) My grandmother is oldcore.
referring to something of a style back in the day (1) , referring to porn with old people (2)
Tom: Dude, the other day I was listening to Conway Twitty, brought back memories.
Bill: That's some oldcore shit!