Unit
Unit may refer to: == General measurement == Unit of measurement, a definite magnitude of a physical quantity, defined and adopted by convention or by law International System of Units (SI), modern form of the metric system English units, historical units of measurement used in England up to 1824 Unit of length == Science and technology == === Physical sciences === Natural unit, a physical unit of measurement Geological unit or rock unit, a volume of identifiable rock or ice Astronomical unit, a unit of length roughly between the Earth and the Sun === Chemistry and medicine === Equivalent (chemistry), a unit of measurement used in chemistry and biology Unit, a vessel or section of a chemical plant Blood unit, a measurement in blood transfusion Enzyme unit, a measurement of active enzyme in a sample International unit, a unit of measurement for nutrients and drugs === Mathematics === Unit number, the number 1 Unit, identity element Unit (ring theory), an element that is invertible with respect to ring multiplication Unit, a tuple of length 0; an empty tuple Statistical unit, a data point on which statistical analysis is performed Unit angle, a full turn equal to an angle of 1 Unit circle, a circle with a radius of length 1 Unit cube, a cube with sides of length 1 Unit fraction, a reciprocal of a positive integer Unit imaginary number, square root of negative 1 ( − 1 ) {\displaystyle ({\sqrt {-1}})} Unit impulse, an impulse of height 1 Unit interval, an interval of distance 1 Unit matrix, a diagonal matrix such that all elements on the main diagonal are 1 and all the others are zero Unit round-off, an upper bound on the relative error due to rounding in floating point Unit set, a singleton, a set with exactly 1 element Unit sphere, a sphere with a radius of length 1 Unit square, a square with sides of length 1 Unit vector, a vector with length equal to 1 Unit type, a type allowing only one value in type theory === Computing === Central processing unit, the electronic circuitry within a computer that carries out the instructions of a computer program GNU Units, a software program for unit conversion Rack unit, a unit of measure most commonly used to define the size of certain computing equipment Unit testing, a method by which individual units of source code are tested == Business == Stock keeping unit, a discrete inventory management construct Strategic business unit, a profit center which focuses on product offering and market segment Unit of account, a monetary unit of measurement Unit coin, a small coin or medallion (usually military), bearing an organization's insignia or emblem Work unit, the name given to a place of employment in the People's Republic of China Telephone card unit. When bought contains a certain amount of units, which make up their own currency for making telephone calls, that may not necessarily correspond to the monetary cost of the actual telephone card.