maincore

Main-Core or just Maincore is used to refer to the central elemental or basic characteristic of something or someone. It is strongly related in use to Large-Core and similar derivatives. It is a portmanteau of Main, which here means the main thing and not a place in USA ---> and Core which is like the kernel or centre of something. (Apple core is a good reference point here to keep you grounded)

Other close derivative or strongly related 'Core' word here is Rudecore

Like, his attitude to toward Jazz music is Maincore. innit!

Other usage might be: At the Trek convention there were some fringe types but there were some real dudes that were Maincore!