Chatter:

Rapid opening and closing of contacts, usually exhibited during extreme vibration and/or shock.

Bifurcated Contact:

A wiping movable contact consisting of spring fingers that grip the fixed contact. Typically found in slide switches.

Clearance (spacing):

Distance through air between electrically live parts of opposite polarity or to ground.

Conductive Rubber:

Elastomer filled with carbon or metallic particles which render the material electrically conductive.