Ground:

Used to indicate a negative side or ground side of a battery or electrical supply (ac or dc).

Insulation Resistance:

The electrical resistance between two normally insulated parts; measured at a specific high potential (1000 Vrms). Typical value for switches is 1 G.

Erosion (Contact):

The transfer or vaporization of contact material resulting from the arc due to breaking or opening the circuit.

Hall Effect Sensor:

An electronic device that changes state (voltage output) when exposed to a magnetic field.

ESD:

Electrostatic discharge, the static charge that is built up that can amount to several thousand volts. Can destroy electronic components.