WordWeb Online

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

See also: alive, animated, bright-eyed [informal], bright-eyed and bushy-tailed [informal], essential, full of beans [informal], indispensable, live

Encyclopedia: Vital, Martha