Plain English Meaning
A flat, layered sheet containing graphite that is built into the front edges of the wings and tail. Electricity flows through it to warm the surface and stop ice from sticking, or to crack ice off once it has formed.
Full Definition
A thin, electrically conductive material made of layers of graphite bonded together with adhesive, embedded in the leading edges of wings and tail surfaces to act as a heating element for electrothermal anti-ice and deice systems. When electrical current flows through the graphite layer, it heats up and either prevents ice from forming or breaks ice loose from the surface.
Context Anchor
Seen in discussions of electrically heated and deice systems, especially on or tail leading-edge surfaces.