An inhalation.
To draw air or any form of gas (either in a pure form, or mixed with small particles in form of aerosols/smoke -sometimes stemming from a medicament) into the lungs, through the nose or mouth by action of the diaphragm.
To eat very quickly.
To draw air into the lungs, through the nose or mouth by action of the diaphragm.
The act of breathing, not necessarily for a sustained period (compare respiration, which is sustained).