Which term refers to a brief summary or outline of a topic?

The term that refers to a brief summary or outline of a topic is "synopsis." A synopsis provides a concise overview or summary that highlights the main points and essential details of the subject matter. It is commonly used in various contexts such as literature, film, and academic writing to give readers a clear understanding of the content without requiring them to engage with the entire work.

In contrast, the other terms do not fit this definition. "Sublimation" pertains to a phase transition in chemistry where a substance changes directly from a solid to a gas, bypassing the liquid state. "Succor" refers to assistance or support, especially in times of hardship or distress, while "subterfuge" involves deceit or trickery used to achieve a goal. None of these words convey the notion of summarizing or outlining a topic, which is why "synopsis" is the appropriate choice.