[n] 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 ostinancy"
[adj] gaping open as if threatening to engulf someone or something; "the yawning mine shaft"; "a yawning abyss"
[adj] with the mouth wide open indicating boredom or sleepiness; "a yawning congregation"