Pronunciation: (vīt'l),[key] —adj. 1. of or pertaining to life: vital processes. 2. having remarkable energy, liveliness, or force of personality: a vital leader. 3. being the seat or source of life: the vital organs. 4. necessary to life: vital fluids. 5. necessary to the existence, continuance, or well-being of something; indispensable; essential: vital for a healthy society. 6. affecting the existence, well-being, truth, etc., of something: a vital error. 7. of critical importance: vital decisions. 8. destructive to life; deadly: a vital wound.