Plain English Meaning
How easily electricity can move through a material. Some materials let it pass through with almost no trouble; others block it.
Full Definition
A measure of how readily a material allows electric current to flow through it. Materials with high electrical conductivity (such as aluminum and copper) carry current with little resistance, while materials with low conductivity (such as composites, rubber, or dry wood) resist the flow of current.
Context Anchor
Seen in discussions of lightning strike protection, especially when comparing metal aircraft structures with composite structures that may need added conductive material.
Derivation
From the Latin 'conducere,' meaning 'to lead or bring together.' A material with high conductivity 'leads' electricity through itself easily.