What is the term for ignition that occurs when a flame or spark is applied to a heated combustible material?

The correct term for ignition that occurs when a flame or spark is applied to a heated combustible material is piloted ignition. This process involves an external source of ignition, such as a flame or spark, being introduced to a material that has already been heated to a certain temperature, making it more susceptible to burning. In this scenario, the pre-heated material reaches a point where its surface can ignite upon receiving the additional energy from the external igniter.

In contrast, autoignition refers to a process where a material ignites without any external flame or spark, simply due to high temperatures. Spontaneous combustion describes a situation where a material ignites due to internal heat buildup, often from an exothermic reaction. Thermal ignition, while sometimes used in discussions of combustion, is not the accepted term for ignition due to an external flame or spark in scientific definitions. Therefore, piloted ignition is the precise term for the scenario described in the question.