contours

noun

1. 1

   An outline, boundary or border, usually of curved shape.

   “the low drag contour of a modern automobile”

2. 2

   A line on a map or chart delineating those points which have the same altitude or other plotted quantity: a contour line or isopleth.

3. 3

   A speech sound which behaves as a single segment, but which makes an internal transition from one quality, place, or manner to another.