水泡・水沫|すいほうsuihou[0]heiban (flat)

1. nounfoam; bubble
2. nounnothing

• Synonym泡あわNeutralThe everyday, most general word for foam or bubbles, as in 「石けんの泡」. 「水泡」 itself is mostly limited to the set phrase 「水泡に帰す」, for efforts coming to nothing.
• Synonym泡沫うたかたWrittenA literary, elegant word for bubbles on the water's surface, used metaphorically for life's transience, as in 「うたかたの恋」.
• Related気泡きほうNeutralAir bubbles in a liquid or solid, as in 「ガラスの気泡」; leans toward scientific or technical description.
• RelatedバブルNeutralA loanword meaning bubbles, and by extension the bubble economy, as in 「バブル崩壊」.

For everyday foam or bubbles, say 「泡」. For efforts coming to nothing, the written metaphor is 「水泡に帰す」. For something fleeting and illusory, use 「うたかた」; for the bubble economy, 「バブル」.

Usage comparisons are AI-assisted and cross-checked by multiple models; for study reference only

1. 水面すいめんなどの水の泡みずのあわ。
2. 儚はかないこと。
3. 無駄むだになること。