metatopic means an overarching subject or theme of a book, document, or a collection of topics, which serves as the central organizing principle for its index. Lexicurio rates it Sui generis — a strength score of 100 out of 100.
Etymology
From meta- + topic.
noun
- An overarching subject or theme of a book, document, or a collection of topics, which serves as the central organizing principle for its index.