linear

A proportional relation between two quantities, e.g. in the equation y = cx, c is the constant y/x and states that y is a linear function of x. The term comes from the straight line with which such a function can be visualized within x-y coordinates. The notion of linearity is generalized to relations between many quantities, expressed in the form of linear equations, to a concept of time that progresses from an indefinite past to an indefinite future without parallel paths or loops, and to a causal network or lattice which proceeds directionally from antecedents to consequences without feedback. (Krippendorff )