渊源
yuānyuán · HSK 7
origin
🌊 渊 deep pool + 源 spring/source = the deep wellspring water flows from = origin
Both characters carry the water radical 氵. 渊 is a deep pool and 源 is a spring head, so the pair literally points back to where water begins, which extends to the origin or source of anything. The doubled yuán-yuán sound makes it easy to recall as a paired set phrase.