纲要 (gāng yào) literally combines 纲 (gāng), meaning 'main rope' or 'guiding principle', and 要 (yào), meaning 'essential' or 'key point'. Together, they form a formal noun meaning 'compendium' or 'essential outline' — a concise yet comprehensive summary that captures the core structure and critical points of a larger body of knowledge. It emphasizes hierarchy and centrality: the '纲' represents the overarching framework, while the '要' pinpoints indispensable elements within it.

This term is commonly used in academic, administrative, and educational contexts — for example, course syllabi, policy documents, research proposals, or taxonomic overviews. In biology, 纲要 often appears in titles like 'Animal Classification Compendium' (动物分类纲要), where it signals a systematic, authoritative distillation rather than a casual summary. It carries a formal, scholarly register and is rarely used in spoken, informal conversation.