pow·er 
(pouər)
(pouər)n.
1.
a. The ability or capacity to act or do something effectively: Is it in your power to undo this injustice?
b. often powers A specific capacity, faculty, or aptitude: her powers of concentration.
2.
a. Physical strength or force exerted or capable of being exerted: the power of the waves. See Synonyms at strength.
b. Effectiveness at moving one's emotions or changing how one thinks: a novel of great power.
3.
a. The ability or official capacity to exercise control; authority: How long has that party been in power?
b. The military strength or economic or political influence of a nation or other group: That country projects its power throughout the region.
c. A country, nation, or other political unit having great influence or control over others: the western powers.
4.
a. A supernatural being: the powers of evil.
b. powers Christianity The sixth of the nine orders of angels in medieval angelology.
5.
a. The energy or motive force by which a physical system or machine is operated: turbines turned by steam power; a sailing ship driven by wind power.
b. The capacity of a system or machine to operate: a vehicle that runs under its own power.
c. Electrical or mechanical energy, especially as used to assist or replace human energy.
d. Electricity supplied to a home, building, or community: a storm that cut off power to the whole region.
6. Physics The rate at which work is done, expressed as the amount of work per unit time and commonly measured in units such as the watt and horsepower.
7. Electricity
a. The product of applied potential difference and current in a direct-current circuit.
b. The product of the effective values of the voltage and current with the cosine of the phase angle between current and voltage in an alternating-current circuit.
8. Mathematics
a. See exponent.
b. The number of elements in a finite set.
9. Statistics In a statistical test, the probability of correctly rejecting the null hypothesis when it is false.
10. A measure of the magnification of an optical instrument, such as a microscope or telescope.
11. Chiefly Upper Southern US A large number or amount. See Note at powerful.
12. Archaic An armed force.
adj.
1. Of or relating to political, social, or economic control: a power struggle; a power base.
2. Operated with mechanical or electrical energy in place of bodily exertion: a power tool; power car windows.
3. Of or relating to the generation or transmission of electricity: power companies; power lines.
4. Informal Of or relating to influential business or professional practices: a pinstriped suit with a power tie; met with high-level executives at a power breakfast.
tr.v. pow·ered, pow·er·ing, pow·ers
Idiom: To supply with power, especially mechanical or electrical power.
powers that be
Those who hold effective power in a system or situation: a plan vetoed by the powers that be.
[Middle English, from Old French pooir, to be able, power, from Vulgar Latin *potēre, to be able, from Latin potis, able, powerful; see poti- in the Appendix of Indo-European roots.]