The kanji 枢 generally conveys the idea of a central or pivotal point, a core, or a hinge. It often refers to something essential or the most important part of a structure or system. This can apply to physical objects, like the central axis of a rotating door, or abstract concepts, such as the core of an idea or organization.

・On-yomi (音読み): スウ (sū) ・Kun-yomi (訓読み): None

⚫︎ 枢軸 (sūjiku) Translation: pivot; axis; central point ⚫︎ 枢機 (sūkī) Translation: the core; central machinery; key organization ⚫︎ 中枢 (chūsū) Translation: center; hub; core; the central nervous system

The kanji 枢 is a 形声文字 (keisei moji), a phono-semantic compound character. The left side is 木 (ki) which means "tree" or "wood," indicating the semantic component (meaning related to wood). The right side is 区 (ku), which means "area" or "region" and functions phonetically, indicating the pronunciation スウ (sū). The original meaning of 枢 was likely the hinge of a door, the wooden part of a door that allows it to turn. Over time, it developed to mean the core or pivotal point of something, whether physical or abstract.