(biology) release of material by splitting open of an organ or tissue; the natural bursting open at maturity of a fruit or other reproductive body to release seeds or spores or the bursting open of a surgically closed wound
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"