puzzling

Concise Oxford English Dictionary © 2008 Oxford University Press:
puzzle/ˈpʌzl/

▶verb

• 1 confuse (someone) on account of being difficult to understand.

• 2 think hard about something difficult to understand.

▶noun

• 1 a game, toy, or problem designed to test ingenuity or knowledge.

• 2 a puzzling person or thing.

– derivatives
puzzlement noun,
puzzler noun,
puzzling adjective,
puzzlingly adverb.

– origin C16: of unknown origin.