1. Dimensions, quantity, or a capacity as determined by comparisons with certain standards.
2. A unit specified by a scale; such as, a degree, or by variable conditions, for example, room temperature.
3. A system of measurement including the metric system.
4. To ascertain the dimensions, quantity, or capacity of something.
5. To mark off or apportion, usually with reference to a given unit of measurement.
6. A standard used for determining the dimensions, area, volume, or weight of something.

1. The amp, short for ampere, is the amount of electric current flowing in a wire.

The electric current is measured in electrons per second.

2. The ohm is a measure of resistance to current.

The higher the resistance at a given voltage, the less current flows. Higher resistance can be obtained by using thinner wires or by using materials which are less efficient conductors.

3. The volt is a measure of the potential energy of the source or the "pressure" pushing electrons through the wire.
4. A watt is a unit of electric power or the speed at which an electric current can function.

Electric energy is expressed in units called watt-hours, which is what is usually referred to in everyday speech when someone says "watts".

A 100-watt light bulb, that operates for one hour, uses one watt-hour and electricity which is used in a home is normally metered in kilowatt-hours, or thousands of watt-hours.

Our universe gives measurements of length, weight, and area in metric units because scientists use the metric system in their work.

Temperatures are measured in degrees Celsius (°C), also called centigrade, and in kelvins (sometimes abbreviated K).

Kelvins are used by astronomers to describe very high temperatures; such as, those in the sun and other stars.