A
fighter aeroplane, such as
F-117A, that isn't
visible to
radar.
Construction of such plane involves, among other things, covering the surface with material that doesn't reflect the radar beam well, careful planning of heat exhaust and minimizing radio usage.
The result is often kind of cumbersome otherwise, but you've got to sacrifice something to get optimal results on other areas...
In MicroProse's "F-19 Stealth Fighter", the plane is aerodynamically as nice as a frying pan. F19SF was a simulator that the real F-117A pilots thought was very accurate flight-model-wise (The plane the game is about, designated as F-19 Nighthawk, never existed, though). I played F-19 Stealth Fighter a lot back in the day; I was a bit shocked when I got Falcon 4.0 and noticed that yes, that thing actually flies nicely unlike F-19...