1) Contour line 2) Isarithm 3) Isopleth 4) Line 5) Line on a chart 6) Map line between equal points 7) Word play 1) Isarithm 2) Isobar 3) Isochrone 4) Isohel 5) Isopleth 6) Isotherm 7) Isothermic 
An isogram (also known as a `nonpattern word`) is a logological term for a word or phrase without a repeating letter. It is also used by some to mean a word or phrase in which each letter appears the same number of times, not necessarily just once. Conveniently, the word itself is an isogram in both senses of the word. In the book Language on Va.....
line connecting points on a map having some similar feature
[n] - a line drawn on a map connecting points having the same numerical value of some variable
isogram A proposed general term for lines on a diagram, etc. indicating equality of some physical condition or quantity, as isotherms, isobars, etc.
isopleth noun a line drawn on a map connecting points having the same numerical value of some variable
a line representing equality with respect to a given variable, used to relate points on maps, charts, etc. Also called