Which term refers to substances that do not conduct heat or electricity?

The term that refers to substances that do not conduct heat or electricity is "insulators." Insulators are materials that prevent the flow of electrical current and thermal energy. This characteristic is crucial in various applications, such as electrical wiring and thermal management systems. For example, rubber, glass, and most plastics serve as effective insulators because they do not have free-moving charged particles, which are necessary for conducting electricity.

Conductors, on the other hand, are materials that allow electricity and heat to flow easily. Metals like copper and aluminum are prime examples of conductors. Semiconductors have properties that fall between insulators and conductors, meaning they can conduct electricity under certain conditions but not as efficiently as conductors. Electrolytes are substances that conduct electricity when dissolved in water due to the movement of ions, which again highlights their ability to conduct rather than insulate. Thus, insulators are specifically defined by their role in preventing conduction, making them the correct answer to the question.