To open the mouth widely and take a long, rather deep breath, often because one is tired or bored, and sometimes accompanied by pandiculation.
I could see my students yawning, so I knew the lesson was boring them.
To say while yawning.
To present a wide opening.
Death yawned before us, and I hit the brakes.
To open the mouth, or to gape, through surprise or bewilderment.
To be eager; to desire to swallow anything; to express desire by yawning.
to yawn for fat livings