水蒸気|すいじょうきsuijouki[3]nakadaka (mid-high)

1. nounwater vapour; water vapor; steam
   熱ねつは水みずを水蒸気すいじょうきに変かえる。↗

   Heat turns water into steam.

• SynonymスチームNeutralLoanword for steam, also covering steam heating, as in 「スチームアイロン」 or 「スチームを当てる」; 「水蒸気」 is the more scientific term.
• Synonym蒸気じょうきNeutralGas formed when a liquid evaporates; also a short form of 「水蒸気」, as in 「蒸気機関車」. 「水蒸気」 is the term for meteorology and chemistry.
• Synonym湯気ゆげNeutralThe visible white steam rising from something hot, as in 「湯気が立つ」. 「水蒸気」 is the scientific word, usually for vapour you cannot see.
• Related湯煙ゆけむりNeutralSteam rising from hot springs or baths, seen often in onsen advertising; 「水蒸気」 is the scientific term.

Use 「水蒸気」 for water vapour in scientific or meteorological contexts. For steam in general, as in 「蒸気機関車」, use 「蒸気」; for the white steam you can see, 「湯気」; over hot springs, 「湯煙」; and the loanword 「スチーム」 for steam heat and appliances.

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

1. 水みずが気化きかしたもの。
2. 1の温度おんどがやや下さがって、霧きり状じょうに見みえるもの。ゆげ。