noun
A concise overview or digest of a topic, often used in academic or formal contexts.
この本は日本史の要説をまとめたものです。
This book is a summary of the outline of Japanese history.
講義の前に要説を配布します。
I will distribute an outline before the lecture.
Compound of 要 (essential point) and 説 (explanation). The exact historical derivation is uncertain, but the spelling is conventionally associated with the meaning 'outline' or 'summary'.