A better term for a "contour plot". Most contour plots are isopleths, where each line is a trace along a contour of all the points with the same value.

''The man in the street typically says "isopleth map" when of course they truly mean "isocline map", but U.S.G.S specialists sneer at such usage.''

An isocline is a syncline or anticline so deeply folded the rock strata parallel each other on both sides.

''Right, so the plinths line up!''

''Actually I was just joking, since the man in the street obviously never heard the words "isopleth" nor "isocline" (nor can I see why "isopleth" is somehow preferable to "contour map")''

''And it's cute that you can use a dictionary to quote a definition to try to correct/criticize my humor...''

''Except that if you used an UNABRIDGED dictionary you'd see that I was already using the correct definition. An isocline map is roughly synonymous with a contour map; the isoclinal lines are drawn along points in the diagram with identical values.''

''One can use isoclines to show the boundaries of equal electrical potential surrounding an arbitrarily shaped conductor, for instance; they inherently become less detailed as distance from the surface decreases, which puts strict theoretical limits on many kinds of remote sensing. (I.e. you can't distinguish objects purely from a 3d isocline surface taken at a significant fraction of a radius from the object; an infinite number of objects generate the same isoclinal surface.''

* It flashed me back to my EE days,  when you get far enough from an object (usually determined by its radius), you get to make the math easier and assume it's a point source.  Now that I have rephased it, I get the feeling that this is very similar, but not exactly the same thing. (expanded, as per request)
** Ah; near field and far field effects in your ever-so-interesting EM part 5: Antennae and Engineers Who Love Them :-) Right, not identical, but they are closely related. An isocline would usually reference an electrostatic field potential, the one that falls off 1/r with distance rather than 1/r^2
** Without a lens, pretty much all remote sensing suffers a similar limit. Lenses can bring a remote object into focus due to angular phase reversal of the EM wavefront. There's nothing similar one can do with a static field, so each measured point is just the triple integral of the contribution from every point in the surrounds, and there's no measurement of phase, either, unlike in holograms (which measure at least phase relative to reference, not absolute phase, but...I digress...) -- it's all just a blur.

** Sorry I'm phrasing this badly, my mind is on non-EM/physics stuff right now...

http://mathworld.wolfram.com/Isocline.html

http://www.dictionarybarn.com/ISOCLINE.php

too large to in-line:  sunflower.bio.indiana.edu/~bbrodie/webpics/hotspots%20isocline%20only.jpg (''fixed the long url, didn't check up on copyright issues'')
* thanks.