Definition
A measure of how strongly a given material opposes the flow of electric current, expressed for a standard sample size of the material. Resistivity is a property of the material itself, independent of the size or shape of any particular piece. It is typically given in ohms per a defined cross-section and length (for example, ohms per circular-mil-foot for wire).
Plain English
How much a material naturally resists electricity, measured for a standard-sized sample so different materials can be compared fairly.
Context Anchor
Seen in aircraft electrical-system discussions about wire materials, electrical heating, insulation, and unwanted resistance in a circuit.
Derivation
From 'resist' (Latin resistere, 'to stand against') plus the suffix '-ivity', which turns a quality into a measurable property. So 'resistivity' literally means the measurable quality of resisting — in this case, resisting electric current.
Why Pilots Care
A material with high resistivity can create more voltage loss and heat when current flows through it. In aircraft, that matters for wire selection, electrical reliability, and troubleshooting weak or overheating equipment.
Grounding Statement
Copper has low resistivity, so current passes through it easily; rubber has very high resistivity, so it is used to block current.
Intuition Check
Resistivity is not the same as resistance. Resistance describes one specific wire or part; resistivity describes the material itself.
Example Sentence 1
Copper is used for most aircraft wiring because its low resistivity allows current to flow with minimal loss.
Example Sentence 2
High resistivity in the composite skin helped prevent damage from lightning strikes.