The core meaning of the kanji 定定 is "to decide," "to determine," "to fix," or "to establish." It implies setting something in a specific state or condition, making a decision, or ensuring something remains stable. It encompasses the idea of making something permanent or definite.

・On-yomi (音読み): テイ (tei) ・Kun-yomi (訓読み): さだ（める） (sada(meru)) - to decide, to determine; さだ（まる） (sada(maru)) - to be decided, to be settled

⚫︎予定（よてい） Translation: Schedule; plan; arrangement ⚫︎決定（けってい） Translation: Decision; determination ⚫︎安定（あんてい） Translation: Stability; steadiness

The kanji 定定 is a phono-semantic compound (形声文字). The left side is 宀, the "roof" radical (representing a house or enclosure) and the right side is 正 (sei/shou), meaning "correct" or "upright." The original meaning possibly implied setting something "correct" or "fixed" within a "house" or a set location. Over time, the meaning evolved to represent the concept of deciding, fixing, and establishing. The character's formation is a simplified version from older forms, which can be traced back through its evolution in seal script (篆書, tensho).