Definition 1 of 2
Plain English Meaning
How well something lets electricity flow through it. Salt water lets it flow easily; dry sand or rock does not. For radio, surfaces that conduct well help the signal travel further along the ground.
Full Definition
The ability of a material or surface to carry an electric current. In the context of radio wave propagation, it refers to how well the Earth's surface (soil, water, terrain) conducts the electrical component of a passing radio wave, which affects how far and how cleanly low-frequency ground waves can travel.
Context Anchor
Seen in instrument flying when studying how radio signals travel over land, water, and different types of terrain.