Meaning of KERNEL in English

KERNEL

n. 1 grain, seed, pip, stone; nut, meat, US nut-meat Try to extract the walnut kernel without breaking it 2 centre, core, nucleus, heart, essence, quintessence, substance, gist, pith, nub, quiddity Let's get down to the kernel of the problem

Oxford thesaurus English vocab.      Английский словарь Оксфорд тезаурус.