In sociology, power is when a person tells another to do something, and they do it. This might also be called influence.
In politics, power is when one country makes another country do something. This kind of power might come from having a big army, or having a lot of money.
Power can mean electrical power. This kind of power usually comes from power plants or generators.
In statistics, the statistical power of a test is how likely the test is to say something is true when it is really false.
In mathematics, "power" is an operation (something that can be done to numbers). In the expression 23, we say that 2 "is raised to the power of 3". This is also known as exponentiation.
The Chinese call it chi. The Japanese call it kiai.