Adjectives

(a)crucial, importantof extreme importance; vital to the resolution of a crisis“a crucial moment in his career”, “a crucial election”, “a crucial issue for women”
(s)crucialhaving crucial relevance“crucial to the case”
(s)all-important, all important, crucial, essential, of the essenceof the greatest importance“the all-important subject of disarmament”, “crucial information”, “in chess cool nerves are of the essence”