meaning of vital
vital, adj necessary to or pertaining to life. vital capacity, n a measurement of the amount of air that can be expelled at the normal rate of exhalation after a maximum inspiration, representing the greatest possible breathing capacity.ital capacity. the greatest volume of gas that, following maximum inspiration, can be expelled during a complete, slow, unforced expiratory maneuver; equal to inspiratory capacity plus expiratory reserve volume. This is a commonly made and practicable measurement in humans but is not so in animals.