yawn

(noun) an involuntary intake of breath through a wide open mouth; usually triggered by fatigue or boredom. Synonyms: yawning, oscitance, oscitancy. Examples: "He could not suppress a yawn." "The yawning in the audience told him it was time to stop." "He apologized for his oscitancy."

(verb) utter a yawn, as from lack of oxygen or when one is tired. Example: "The child yawned during the long performance."

(verb) be wide open. Synonyms: gape, yaw. Example: "The deep gaping canyon."