What is the X in X-mas?
exhalation ex·ha·la·tion (ěks'hə-lā'shən, ěk'sə-)
The act or an instance of breathing out. Also called expiration.
The giving forth of gas or vapor.
Something, such as air or vapor, that is exhaled.
The act of breathing out air. During exhalation, the diaphragm relaxes and moves upward, causing compression of the lungs and an outward flow of air. Also called expiration. Compare inhalation.