流す

1. Origins, structure, and basic meaning

• Structure: 流す is read as ながす and is a verb meaning to let water flow or to shed tears.
• Basic usage: Mark what is made to flow with を, as in 水を or 涙を, and use the context to distinguish physical movement from emotional expression.

2. Common pitfalls and similar expressions

• Sending water through something
  • 水を流す means that someone causes water to flow through a channel or to another place. Example: 細い溝に水を流して、木の船を浮かべました。
• Shedding tears
  • 涙を流す means to shed tears and can occur from joy as well as sadness. Example: 彼はうれしさのあまり涙を流すこともありました。