a plate or other attachment for deflecting a flow of air, water, heat, etc.:an underbody deflector to smooth airflow near the rear suspension [as modifier]:a metal deflector plate to stop the controls getting too hot
an electrode in a cathode ray tube whose magnetic field is used to deflect a beam of electrons on to a phosphor screen to form an image.
deflector in other Oxford dictionaries
Definition of deflector in the US English dictionary