1. The ability, strength, and capacity to do something: A good microscope needs high quality power to see microscopic structures.
2. Physical force or strength: Jerry needed a lot of power to hit the baseball far enough into the field in order for a home run!
3. Control and influence over other people and their actions: In her career, Jill reached a high position with lots of power and influence.
4. The political control of a country, exercised by its government or leader: The people wanted to overthrow the present government because they were exercising unfair and brutal power over the citizens.
5. The authority to act or to do something according to a law or rule: Mr. Smith had a debt problem, and the bank said that it was within his power to resolve the unfavourable situation on his bank account.

Police have the power to arrest criminals.
6. A country that has military or economic resources and is considered to have political influence over other countries: There have always been nations whose power has been used to have great impact and control over smaller and weaker nations.
7. The ability to influence people's judgments or emotions: Mr. T. used his rhetorical power to move and sway the masses of people to accept and have trust in his views as being the truth!
8. A measure of the rate of doing work or transferring energy: Power is usually expressed in terms of "wattage" or "horsepower".
9 Energy produced by electricity or fuel: Power is generated when a motor uses electrical energy or fuel instead of relying on manual labor.
10. Etymology: from Anglo-French pouair, Old French povoir, noun use of the infinitive in Old French, "to be able" from earlier podir, from Latin potis, "powerful".

A measurement of the output of RFID reader antennas used in the United States and elsewhere: An effective isotropic radiated power is the assessment of the power of the signal departing from a satellite antenna in a certain direction.

EIRP is usually expressed in watts.

A measurement of the output of RFID reader antennas used in Europe and elsewhere: An effective radiated power is the same as "equivalent radiated power" and is an IFEE standardized meaning of directional radio frequency power.

ERP is usually expressed in watts and is not the same as EIRP.