1.
confluence, merging (of rivers, roads)
The point where rivers, roads, or traffic lanes come together and merge into one.
ここで二つの川が合流する。
Two rivers merge here.
高速道路の合流地点は事故が多い。
There are many accidents at highway merging points.
渋滞の原因は合流レーンの混雑だった。
The cause of the traffic jam was congestion at the merging lane.
2.
joining up, meeting up, linking up
People or groups coming together to join forces, meet at a point, or unite for a common purpose.
駅前で友人と合流した。
I met up with a friend in front of the station.
別々に出発して現地で合流しよう。
Let's leave separately and meet up at the destination.
二つのチームが合流して、大きなプロジェクトに取り組むことになった。
The two teams joined forces and will work on a large project together.
COMMON COLLOCATIONS:
- 川が合流する (rivers merge)
- 合流地点 (merging point, confluence)
- 〜と合流する (join up with ~)
- 合流レーン (merging lane)
The physical sense (sense 1) is most commonly used with rivers and roads/traffic. The figurative sense (sense 2) is very common in everyday conversation for meeting up with people.