Undefined (mathematics)
In mathematics, the word undefined has several different meanings, depending on the context. In geometry, simple words such as "point" and "line" are taken as undefined terms. In arithmetic, some arithmetic operations are called "undefined". The most famous example is that division by zero is undefined. Inalgebra, a function is said to be "undefined" at points not in its domain. For example, in the real number system, is undefined for negative .