n. 25B6; noun CRUX, central point, main point, core, heart (of the matter), nucleus, essence, quintessence, kernel, marrow, meat, pith; gist, substance; informal nitty-gritty.
NUB
Meaning of NUB in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012