Linearity

In mathematics, linearity names two related but distinct properties, the linearity of a function or mapping and the linearity of a polynomial. A linear function, such as one mapping the real line to a line through the origin in the plane, is compatible with addition and with scaling by a constant, the same superposition property that generalizes to functions of more than one variable. A polynomial is linear when its degree is less than two, which is why the graph of a one variable polynomial of that degree is a straight line, and the word itself comes from the Latin linearis, pertaining to a line.