big, deep, huge
loud, noisy
stifled
collective (figurative)
The speech was greeted with a collective yawn from the press gallery.

fight back, hold back, stifle, suppress
He struggled to stifle a yawn.

give, let out
The little boy gave a huge yawn.

conceal
He tried to conceal his yawn behind his hand.

escape
A loud yawn escaped my lips.

with a yawn

hugely, widely
He sat up and yawned hugely.

loudly

make sb
hear sb

at
He got fed up with people yawning at him when he talked about his job.

can't stop yawning
I was so tired I couldn't stop yawning.