Definitions:
the tough central part of various fruits, containing the seeds

the part of something that is central to its existence or character

the dense central region of a planet, especially the nickel–iron inner part of the earth.

central to the existence or character of someone or something

denoting or relating to a figure for inflation that excludes certain items, chiefly food and energy, that are subject to sudden and temporary price fluctuations

remove the tough central part and seeds from (a fruit)

(in the us) congress of racial equality.