轮廓
as a shape with an edge but without any details
The mountain was visible only in outline as the light faded. 光线暗了下来，只能看见山的轮廓。
Even in outline, the iconic building is instantly recognizable.
A figure at the back of the room has been painted over by the artist but is still faintly visible in outline.
In this light, you can make out one or two tall buildings in outline.
Most of the items are drawn in outline.
See also: outline noun (SHAPE)