The Oxford Thesaurus An A-Z Dictionary of Synonyms - vital adj.

1) imperative, essential, necessary, needed, requisite, required, indispensable, mandatory, compulsory, cardinal, fundamental, basic, critical, crucial, central, pivotal: Air and water are vital for the existence of most known organisms. 2 important, key, central, critical, crucial, life-and-death or life-or-death, pivotal, paramount, main: In an emergency, the captain must make the vital decision whether to abandon ship. This is a matter of vital concern for us all. 3) lively, full of life, vivacious, spirited, vigorous, dynamic, alive, animated, brisk, energetic: We have lost a vital member of the community. She took a vital interest in community affairs. 4) invigorating, quickening, life-giving, animating, vitalizing, reviving, vivifying, enlivening, rejuvenating: I could feel the vital energies returning to my limbs.