line drawing 
noun
A drawing done using only narrow lines, without blocks of shading.The first is a monochrome line drawing, now in the National Maritime Museum at Greenwich, which accompanied the specification....
- In the patinated bronze sculpture Sleeping Muse, for example, he renders the image of Brancusi's sculpture of the same name as a freestanding line drawing.
- Three limpid watercolors reveal their development through a few washes applied to a pencil or ink line drawing, providing more graphic than chromatic complexity.