Definition

The act of exposing your silhouette against the horizon, making yourself an obvious target. A fundamental tactical error taught on day one but somehow still happens.

Example Usage

Don't skyline yourself on that ridgeline—move along the military crest instead.

Origin

Basic infantry tactics and movement terminology

Fun Fact

Skylining yourself is such a basic mistake that it's often used metaphorically to describe any obvious, amateur error.

Source: Infantry tactics and field craft