‘裁定’ is a formal legal term meaning 'to rule' or 'to adjudicate'—typically used when a judge, tribunal, or authorized body makes an official decision on a matter, especially in civil or administrative cases. The character 裁 (cái) conveys the idea of cutting, selecting, or deciding after careful judgment; 定 (dìng) means 'to fix', 'to settle', or 'to determine'. Together, they emphasize a binding, authoritative conclusion reached through deliberation and procedure.

This word appears almost exclusively in legal, judicial, or official administrative contexts—not in casual speech. It’s commonly found in court documents, news reports about lawsuits, or government announcements. While it can function as a verb (e.g., 法院裁定…), it more frequently serves as a noun meaning 'ruling' or 'adjudication' (e.g., 一项裁定). Unlike colloquial terms like 决定 (juédìng, 'decision'), 裁定 implies legal weight, finality, and procedural legitimacy.