baffle
noun.
a flat plate that controls or directs the flow of fluid or energy
Synonym: baffle board
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
verb.
hinder or prevent (the efforts, plans, or desires) of
What ultimately frustrated every challenger was Ruth's amazing September surge|foil your opponent
verb.
restrain the emission of (sound, fluid, etc.)
Synonym: regulate