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1. Urgently needed; absolutely necessary
   "vital for a healthy society"; "of vital interest"
   - critical
    
2. Performing an essential function in the living body
   "vital organs"; "blood and other vital fluids"; "the loss of vital heat in shock"; "a vital spot"
   - life-sustaining
    
3. Full of spirit
   "a vital and charismatic leader"
   - full of life, lively
    
4. Manifesting or characteristic of life
   "a vital, living organism"; "vital signs"

See also: alive, animated, essential, indispensable, live, vitality, vitalize, vitally, vitalness

Encyclopedia: Vital Vital, Abbot of Savigny