contorno

Italian contorno came from contornare, 'to go around, to turn around,' built from Latin con- ('together, around') and tornare ('to turn on a lathe'). The root image is of a lathe spinning and a tool tracing the outer edge of the object being shaped. A contour is the line the tool follows — the boundary between the thing and everything that is not the thing.

French borrowed contour in the 1560s, and it became a term of art — literally. Painters and draftsmen used contour to describe the outline of a figure, the edge where form meets background. Leonardo da Vinci wrote about contorno in his painting treatises. The contour was the first thing an artist drew and the last thing a viewer noticed: it defined the shape while remaining invisible in the finished work.

English adopted contour in the 1660s and kept it in the arts for a century before the word expanded. Cartographers began drawing contour lines on maps in the 1770s — lines connecting points of equal elevation, making the shape of the land visible on a flat surface. The artist's outline became the geographer's tool for seeing terrain that could not be seen.

Now contour is everywhere: contour maps, contour drawing, body contouring, contour makeup. The word has moved from the artist's studio to the surgeon's table to the bathroom mirror. All these uses share the original Italian meaning: to trace the outer edge of a thing, to find where it ends and something else begins.