What does expiratory mean?
Expiratory is a technical adjective describing anything related to the act of exhaling — the expulsion of air from the lungs. It belongs firmly to the vocabulary of medicine and physiology, where it modifies terms such as flow, volume, and pressure: measurements like peak expiratory flow and forced expiratory volume are standard tools for assessing lung function in conditions such as asthma and chronic obstructive pulmonary disease. The word also labels the expiratory phase of the breathing cycle, when the diaphragm relaxes and air leaves the chest. Derived from the Latin verb spirare ('to breathe'), via expirare ('to breathe out'), it pairs with its natural counterpart inspiratory, which refers to inhaling. Though rarely heard outside clinical settings, expiratory is indispensable to respiratory science, appearing throughout medical literature, diagnostic reports, and discussions of lung capacity. Its precision makes it the unambiguous choice wherever exhalation must be described formally.
adjectiveRelating to or involving the exhalation of air from the lungs; used especially in medical and physiological contexts to describe the phase of breathing during which air is expelled.
- Relating to the exhalation of air from the lungs (medical and physiological use).
"The patient's expiratory flow rate was significantly reduced, suggesting an obstructive airway condition."
"Asthma was confirmed by reduced forced expiratory volume measured over one second."
"During the expiratory phase of respiration, the diaphragm relaxes and air leaves the lungs."
Every time you blow out birthday candles, your peak expiratory flow is on full display — the same measurement doctors rely on to diagnose asthma.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of expiratory
Expiratory derives from the Latin verb spirare, meaning 'to breathe', through the compound expirare, 'to breathe out'. English adopted the noun expiration from Latin-derived French in the sixteenth century, and expiratory emerged later as the corresponding adjective, following the pattern of Latinate adjectives ending in -ory. It shares its root with a family of breath-related words including respiration, spirit, inspire, and perspire.
How expiratory is actually used
Expiratory is a technical term confined almost entirely to medical, respiratory-therapy, and physiological writing. It appears chiefly as a modifier before nouns such as flow, volume, pressure, and phase. In everyday speech, speakers prefer phrases like 'breathe out' rather than this formal adjective.
Easily confused with expiratory
Inspiratory describes the act of breathing air into the lungs, whereas expiratory describes breathing it out.
Expired most commonly means having come to the end of a validity period, while expiratory is a technical adjective relating to exhalation.