an involuntary intake of breath through a wide open mouth; usually triggered by fatigue or boredom; "he could not suppress a yawn"; "the yawning in the audience told him it was time to stop"; "he apologized for his oscitancy"
utter a yawn, as from lack of oxygen or when one is tired; "The child yawned during the long performance"
a high gear used at high speeds to maintain the driving speed with less output power
the state of high or excessive activity or productivity or concentration; "Troops are ready to go into overdrive as soon as the signal is given"; "Melissa's brain was in overdrive"
drive or work too hard; "The teacher is overworking his students"; "Overdriving people often suffer stress"