合流
ごうりゅう · gouryuu · JLPT N2 · noun
join
🌊 合 (join) + 流 (flow) = flows joining together into one
流 means flow and 合 means join, so 合流 literally means flows joining. It is used for rivers meeting and for roads or groups merging into one.
合 — 乛 (lid/roof) + 口 (mouth)
Originally a pictograph of a lidded vessel — a cover (亼) closing over an opening (口) — giving the core sense of 'come together, join, fit.' From 'fit/match' it extended to 'combine, unite, agree' and to measure-word uses. The reading hé reflects this 'joining' meaning.
流 — water radical 氵 + 㐬 (phonetic, child being born)
流 is a semantic-phonetic compound. The water radical 氵 gives the meaning, while 㐬 depicts an infant being born head-down with amniotic fluid, suggesting downward flow. Together they convey water flowing, and by extension 'to flow' or 'current'.