noun

- a graph, usually containing three parallel scales graduated for different variables so that when a straight line connects values of any two, the related value may be read directly from the third at the point intersected by the line.
- any similar graph used to show the relation between quantities, values, numbers, and so on.

noun

- an arrangement of two linear or logarithmic scales such that an intersecting straight line enables an intermediate values or values on a third scale to be read off
- any graphic representation of numerical relationships

n.

- A graph consisting of three coplanar curves, each curve graduated for a different variable so that a straight line cutting all three curves intersects the related values of each variable.