Gage: A measuring instrument for measuring and indicating a quantity.

Gage Block: A block of alloy steel with two gaging surfaces.

Gain: Ratio of output voltage, current, or power to input voltage current or power.

Galvanometer: Meter for detecting or comparing or measuring small electric currents.

Gamma Ray: Electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength.

Gas: The state of matter that has no definite shape of volume.

Gauge Factor: The sensitivity of the strain gauge.

Gauge Pressure (psig): (A measure of the force per area exerted by a fluid using atmospheric pressure as a zero reference.

Gauss: Unit of magnetic induction.

Go and No-Go Gages: Gages that do not measure actual size but merely determine whether parts are within specified limits.

Grain: A measure of mass in the English gravitational system equal to 1/7000th pound.

Gram: A metric unit of weight equal to one thousandth of a kilogram.

Gram-Atomic Weight: The quantity of an element whose weight in grams is numerically equal to the atomic weight of the element.

Gram-Molecular Weight (Gram-Mole): The relative molecular weight of a compound, expressed in grams.

Graticule: A network of fine lines, dots, cross hairs, or wires in the focal plane of the eyepiece of an optical instrument.

Gravitational Acceleration: The acceleration due to the force of gravity.

Guardband: Also called a frequency guard band, a narrow frequency band between adjacent channels in multiplexing that is kept unused to prevent the channels from overlapping and causing crosstalk among modulated signals.