Three-drops water radical on the left, side-form of
水. The indexing radical, marking
洙 as a hydronym - the Zhu River in Shandong, the small stream beside which Confucius taught. The pair
洙泗 (Zhu and Si rivers) became a literary shorthand for the Confucian school itself. Same water-family:
河 river,
江 large river,
湖 lake.
