poker-faced
I can never have a poker face. Anybody looking at me can tell exactly what I'm thinking.
The high bidder kept a poker face after being declared the winner.
She tells the women to practice their poker face so they won't draw attention if they screw up.

SMART Vocabulary: related words and phrases

Not showing or feeling emotions
anodyne
anti-sentimental
belie
bite
bite your lipidiom
frozenly
glaze
hard-bitten
hardened
icily
phlegmatically
reserved
reservedly
sphinx-like
stiff upper lip
unmoved
unprocessed
unresponsive
unresponsively
unresponsiveness

You can also find related words, phrases, and synonyms in the topics:

Lacking humour

poker face | American Dictionary

poker face
noun[ C ]
us/ˈpoʊ·kər ˌfeɪs/
an expression on someone's face that does not show what the person is thinking or feeling

poker-faced

adjective, adverb
He stared at us poker-faced.