Synonyms of life-and-death

2 Syllables
pressing, urgent, heat-on, serious, heaton, vital, crucial
3 Syllables
important, critical, hurry-up, pivotal, paramount, essential, earth-shaking, meaningful
4 Syllables
high-priority, significant, all-important, consequential, determining, earth-shattering
5 Syllables
imperative, indispensable