noun
logic; reasoning; line of argument
Refers to the logical structure or coherence of an argument, explanation, or thought process. Often used in the phrase 理路整然と (in a clear and logical manner).
彼の説明は理路整然としていて、とてもわかりやすい。
His explanation was clear and logical, making it very easy to understand.
その主張には理路がない。
That argument lacks logic.
Compound of 理 (logic, reason) and 路 (path, route), literally 'path of reason'. The exact historical derivation is uncertain, but the word has been used in Japanese since at least the early modern period to denote logical coherence.