poser

/ˈpoʊzər/

poser

BrE /ˈpəʊzə(r)/

NAmE /ˈpoʊzər/

(informal)

a difficult question or problem

SYN puzzler

(also pos·eur) (disapproving)

a person who behaves or dresses in a way that is intended to impress other people and is not sincere