puzzle, puzzler, mystifier, teaser (noun)
a particularly baffling problem that is said to have a correct solution
"he loved to solve chessmate puzzles"; "that's a real puzzler"
a game that tests your ingenuity
perplex, vex, stick, get, puzzle, mystify, baffle, beat, pose, bewilder, flummox, stupefy, nonplus, gravel, amaze, dumbfound (verb)
be a mystery or bewildering to
"This beats me!"; "Got me--I don't know the answer!"; "a vexing problem"; "This question really stuck me"
be uncertain about; think about without fully understanding or being able to decide
"We puzzled over her sudden departure"
riddle, conundrum, enigma, brain-teaser (noun)
a difficult problem
a coarse sieve (as for gravel)
pierce with many holes
"The bullets riddled his body"
set a difficult problem or riddle
"riddle me a riddle"
riddle, screen (verb)
separate with a riddle, as grain from chaff
permeate, pervade, penetrate, interpenetrate, diffuse, imbue, riddle (verb)
spread or diffuse through
"An atmosphere of distrust has permeated this administration"; "music penetrated the entire building"; "His campaign was riddled with accusations and personal attacks"
speak in riddles
explain a riddle