What does dielectric mean?
A dielectric is a material that does not conduct electricity — an insulator that nonetheless interacts with electric fields. When placed in a field, its molecules polarize: their charges shift slightly, allowing the field's influence to be transmitted or stored without any current flowing through the substance. Common dielectrics include glass, ceramics, mica, plastics, dry air, and even vacuum in idealized cases. The word is indispensable in electrical engineering because key device properties are named after it: the dielectric constant measures how well a material stores electrical energy, while dielectric strength indicates how strong a field it can withstand before breaking down. Dielectrics sit between capacitor plates, coat wires, and insulate power lines. Though chiefly a scientific term, 'dielectric' occasionally appears in consumer contexts such as cookware marketed as microwave-safe or nonconductive. Its register is formal and technical, and it functions both as a noun and as an adjective describing anything insulating in this manner.
A nonconducting substance or medium that transmits the effect of an electric field through polarization rather than conduction.
"Teflon serves as an excellent dielectric in high-frequency cables."
Often preceded by the name of the specific material, e.g. 'ceramic dielectric' or 'polymer dielectric'.
Relating to, or having the properties of, a nonconductive medium that supports an electric field by polarization.
"The dielectric layer prevents short circuits between adjacent conductors."
Standard plural; used when referring to different insulating materials collectively or in general statements about classes of materials.
"Ceramics and polymers are among the most widely used dielectrics in modern electronics."
Coined by William Whewell at Michael Faraday's request, 'dielectric' literally means 'that which electricity passes through' — the stuff that lets capacitors work without letting current escape.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of dielectric
The term was coined in the 1830s by English polymath William Whewell at Michael Faraday's request during Faraday's pioneering investigations into electrostatic induction. It combines the Greek prefix dia- ('through' or 'across') with 'electric', conveying the idea of a medium through which electric action is transmitted. Whewell also supplied Faraday with several other enduring terms, including 'electrode', 'electrolyte', and 'ion'. Related words sharing these Greek elements include 'electricity' and 'electron' (from elektron, amber) and 'diagonal' and 'diameter' (from dia-).
Related word forms
How dielectric is actually used
Primarily technical vocabulary used in physics, electronics, and electrical engineering; it is rare in everyday conversation. As a noun it usually appears with a modifier naming the material (e.g., ceramic dielectric), and as an attributive adjective it precedes nouns like constant, strength, or breakdown.
Easily confused with dielectric
A dialect is a regional variety of a language, while a dielectric is an insulating electrical material — they differ by one letter but share no meaning.