noun / verb
pout
POUT/paʊt/
A sulky expression with pushed-out lips, or showing displeasure this way.
The displeased man pushes his lower lip outward in a pout.

Etymology
The origin is uncertain, but suggested relatives concern puffing or swelling. If that connection is correct, the image is of lips pushed outward in displeasure.
In context
couldn't help but pout her little mouth a trace of worry on her pretty face after Wang Xiya got into the car
More examples
- Don't pout just because we have to leave.
- He pouted when his brother changed the channel.
- She tries to hide her pout behind her cup.
Forms
pout · pouts · pouted · pouting
pouty adjective — Showing displeasure with pushed-out lips.