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nomograph nom·o·graph (nŏm'ə-grāf', nō'mə-) or nom·o·gram (-grām')
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.
calculating chart with scales that contain values of three or more mathematical variables, widely used in engineering, industry, and the natural and physical sciences