The phrase "an outline on a map" is correct and usable in written English.
It can be used when referring to a representation or depiction of geographical features or boundaries on a map.
Example: "The outline on the map clearly shows the borders of the national parks in the region."
Alternatives: "a contour on a map" or "a delineation on a map".
Google superimposes an outline on the map, which serves as a search perimeter.
What's distinctive is that it lets users define their own search parameters by superimposing an outline on the map.
The case alleged that one agent drew a red outline on a map of Brooklyn around what areas a white homebuyer should consider living in and talked about the high quality of the schools in the "attractive neighborhoods".
Outlined on a map, it has no recognizable shape.
Each London Underground station was carefully outlined on a map of London.
They wrote a 160,000-word book and, using the iPhone for inspiration, created a "scavenger hunt" element allowing readers to see more story lines by visiting specific locations — like China and Washington, D.C. — that are outlines on a map within the app.
The French Ambassador, and later on the British Ambassador, saw the Fuehrer and outlined on a map the approximate solution which apparently was being proposed by France, England, and Italy as a solution of the Sudeten problem.
Graphical data Data which can be used to create a graphical representation of objects in the real world, i.e. data referring to the outlines on a map.
Itineraries of all participants, including information about means of transport and frequency of trips, were outlined on a map of Murcia.
The allegations centre around a 2014 Facebook post, in which Shah shared a graphic of Israel's outline superimposed on a map of the US under the headline "Solution for Israel-Palestine Conflict – Relocate Israel into United States", with the comment: "Problem solved".
