Akademik

Yawning
The involuntary opening of the mouth with respiration, breathing first inward, then outward. Yawning is often caused by suggestion. Repeated yawning is commonly a sign of drowsiness. It can also sometimes be a sign of depression.
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The act of producing a yawn. SYN: oscitation.

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n.
a reflex action in which the mouth is opened wide and air is drawn into the lungs then slowly released. It is a result of drowsiness, fatigue, or boredom.

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yawn·ing (yawnґing) a deep, involuntary inhalation with the mouth open, often accompanied by the act of stretching. Cf. pandiculation. Called also hiation and oscitation.

Medical dictionary. 2011.