Plain English Meaning
The solid frame piece running down the middle (or side) of the windshield where two windows meet. Because it is not see-through, anything directly behind it is hidden from the pilot's view.
Full Definition
A vertical or angled structural post in an aircraft's windshield that separates two panes of glass or transparent material, creating an opaque strip in the pilot's forward field of view that can hide other aircraft or obstacles behind it.
Context Anchor
Encountered in visual scanning discussions, especially when learning how cockpit structure can create small blind areas in the pilot’s view.
Why Pilots Care
It creates a persistent central blind spot that can hide other aircraft, obstacles, or the until the pilot shifts head .