What term describes the amount of air that can be forcibly expelled from the lungs after a deep inhalation?

The correct term for the amount of air that can be forcibly expelled from the lungs after a deep inhalation is known as vital capacity. Vital capacity refers to the maximum amount of air a person can exhale after a maximum inhalation, encompassing both the tidal volume and the expiratory reserve volume. This measurement is important for assessing overall lung function and capacity.

The other terms have specific definitions that do not match the description provided in the question. Dead space refers to parts of the respiratory system where air does not participate in gas exchange, such as the trachea and bronchi. Expiratory reserve volume is the amount of air that can be forcibly exhaled after the end of a normal expiration, but it doesn't account for the deep inhalation. Tidal volume denotes the amount of air inhaled or exhaled in a normal breath, which is typically much less than the vital capacity. Therefore, vital capacity is the appropriate term for what is described in the question.