EXPRESSIONLESS
ADJECTIVES
1928 ► DEADPAN without expression; displaying no emotion → US sl.
ADVERBS
1930 ► DEADPAN in an expressionless, emotionless manner → US sl.
NOUNS
1927 ► DEADPAN an expressionless stare → US sl.
VERBS
1930 ► DEADPAN to speak without expression, esp. in a situation that would normally demand some emotion → sl., orig. US
Lexicophilia 