adjective

(of a person’s face or voice) not conveying any emotion; unemotional.

her face was expressionless

inscrutable,unreadable,deadpan,poker-faced,blank,empty,vacant,emotionless,unemotional,unexpressive,inexpressive,glazed,fixed,lifeless,stony,wooden,impassive,inanimate,unresponsive,dull,dry,toneless,monotonous,drab,boring,tedious,flat,static,unmodulated,unvarying,undemonstrative,devoid of feeling/emotion,apathetic,unimpassioned,uninspiring,weak