adj. 25B6; adjective IMPORTANT, significant, historic, portentous, critical, crucial, life-and-death, decisive, pivotal, consequential, of consequence, far-reaching; informal earth-shattering; formal of moment.
insignificant.
MOMENTOUS
Meaning of MOMENTOUS in English
Concise Oxford thesaurus English vocabulary. Краткий оксфордский словарь английского языка тезаурус. 2012