I. ˈded-ˌpan adjective
Date: circa 1928
: marked by an impassive matter-of-fact manner, style, or expression
a deadpan comedy
• deadpan adverb
II. noun
Date: circa 1930
1. : a completely expressionless face
2. : a deadpan manner of behavior or presentation
III. transitive verb
Date: circa 1942
: to express in a deadpan manner
• dead·pan·ner noun