i Register
In some senses, yawn is marked as obsolete, colloquial. Watch for register when choosing this word.
ADJ
big, deep, huge | noisy | stifled
VERB + YAWN
stifle, suppress
She tried to suppress a yawn during the boring meeting.
give
Sarah gave a wide yawn during the boring lecture and tried to hide it behind her notebook.
conceal
She couldn't conceal her yawn during the long and boring meeting.
PREP
with a ~
ADV
hugely, widely
The cat stretched and yawned widely after waking from its afternoon nap.
VERB + YAWN
make sb | hear sb
PREP
at
My teacher yawned at my presentation, which made me feel quite nervous.