Plain English Meaning

A fine metal screen built into the outer skin of a composite aircraft so that if lightning hits, the electricity can travel across the surface and leave the aircraft instead of punching a hole or frying the systems inside.

Full Definition

Thin layers of woven or expanded metal wire embedded in or bonded to the outer skin of a composite aircraft to provide a conductive path for lightning current. Because composite materials such as carbon fiber and fiberglass do not conduct electricity well enough on their own, the metal mesh allows a lightning strike to flow across the airframe and exit without burning through the structure or damaging internal systems.