# Unit

From Example Problems

The word * unit* means any of several things:

- Unit of measurement or physical unit, a fundamental quantity of measurement in science or engineering.
- Units (computer program), a popular program that does unit conversion.
- Functional unit, a component of a computer system such as the CPU.
- Unit of action, a discrete piece of action (or beat) in a theatrical presentation.
- Multiple unit, a passenger train whose carriages have their own motors.
- United Nations Intelligence Taskforce, a fictional entity in the
*Doctor Who*television series. - Unit, a rock and roll album by the Australian band
*Regurgitator*. - Unit of alcohol, 10 millilitres of pure ethanol in the UK.
- In currency, a unit of money (a monetary unit).
- In a 19-inch rack a
*rack unit*is a standard height of 1.75 inches.

- In mathematics:
- Unit vector, a vector with length 1.
- Unit circle, the circle with radius 1 centered at the origin.
- Unit interval, the interval of all real numbers between 0 and 1.
- Imaginary unit,
*i*, whose square is -1. - Root of unity, a complex number, a power of which is 1.
- Unit (ring theory), an element that is invertible with respect to ring multiplication.
- In category theory, there is a natural transformation called the unit from the identity functor to the composition of two
*adjoint functors*, q.v.

- Group regarded as a distinct entity within a larger group such as in Law & Order: Special Victims Unit or Wikipedia's Counter Vandalism Unit
- Military units, including:

de:Einheit es:Unidad fr:unité ko:단위 io:Unajo ja:単位 pl:Jednostka simple:Unit sl:enota zh:單位