Synonyms of all-important

2 Syllables

urgent, serious, vital, crucial

3 Syllables

important, critical, life-and-death, pivotal, paramount, earthshaking, essential, bottom-line, earth-shaking, meaningful

4 Syllables

significant, earthshattering, bottomline, necessary, consequential, determining, earth-shattering

5 Syllables

imperative, indispensable