水泡

1. Origins, structure, and basic meaning

• Structure: 水泡 is read as すいほう and is a noun for a bubble in water; in 水泡に帰す, it figuratively means that effort or a plan comes to nothing.
• Basic usage: Use 水面に水泡が浮かぶ for literal bubbles and 努力を水泡に帰す for the idiom.

2. Common pitfalls and similar expressions

• Literal bubble and idiom
  • A bubble on water is physical, whereas 水泡に帰す compares lost effort to a bubble vanishing.
• Contrast with 水疱
  • The homophone 水疱 means a blister on the skin, so its spelling differs from 水泡 for a water bubble.