v.
  - involuntarily open one's mouth wide and inhale deeply due to tiredness or boredom.
 - 
[usu. as adj. yawning]
 be wide open:
 a yawning chasm.
 
n.
  - an act of yawning.
 - informal a boring or tedious thing or event.
 
 
  Derivative
  
  Etymology
  OE geonian, of Gmc origin.