trimline

Trimline refers to a boundary or demarcation line, especially one marking where something ends or changes.

In glaciology, a trimline is the visible boundary on a mountainside showing the maximum extent of a glacier—above it, bare rock; below, vegetation or different erosion patterns.

In manufacturing and design, trimline describes the edge where materials meet or are cut: The trimline on the dashboard separates leather from plastic.

Trimline also appears as a brand or product designation suggesting sleek, streamlined design.