n. In electricity and magnetism: The method of surrounding the apparatus inside of the screen with a shield of soft iron, so as to protect it from external magnetic influences.n. The method of surrounding with a shield, cage, or netting made of good conducting material for protection against external electric forces. In large conductors carrying alternating currents, the outside part of the conductor may screen the inside so that less or no current flows in the interior, and the effective resistance of the conductor is thereby increased.