Synonyms of 'yawn'
If you say that something such as a hole or a wound gapes, you are emphasizing that it is big or wide.
A hole gaped in the roof.
The ground opened beneath his feet.
Thesaurus for yawn from the Collins English Thesaurus
If you yawn , you open your mouth very wide and breathe in more air than usual , often when you are tired or when you are not interested in something.