A graphic representation of numerical relations WordNet 3.0 & Open English WordNet

A nomogram, also called a nomograph, alignment chart, or abac, is a graphical calculating device, a two-dimensional diagram designed to allow the approximate graphical computation of a mathematical function. Wikipedia

Analog graphical calculator Wikidata

A diagram in which the relationship between three variables is represented by a straight line or curve for each variable; the value of the third variable corresponding to particular values of the first two is obtained by drawing a straight line through the points on the first two curves that represent particular values of the first two variables and noting the point at which the line intersects the third line or curve. Wiktionary

Diagram in which the relationship between three variables is represented. Wiktionary (translation)

A nomogram. Wiktionary