蒸気

1. Origins, structure, and basic meaning

• Structure: 蒸気 is a noun read じょうき, meaning steam or water vapor produced through heating.
• Basic usage: It can describe white steam rising from a pot or an old steam locomotive releasing vapor as it moves.
  • 鍋の蓋を開けると白い蒸気が上がった。 says that white steam rose when the pot lid was opened; 古い機関車が蒸気を吐きながら進む模型を見た。 says that the speaker saw a model of an old locomotive moving while releasing steam.

2. Common pitfalls and similar expressions

• 蒸気が上がる
  • が marks the white steam as what rose from the pot.
• 蒸気を吐きながら
  • を marks steam as what the locomotive releases, and ながら shows that releasing it and moving happen together.
• 蒸気 and 湯気
  • 蒸気 broadly covers steam in technical and locomotive contexts, while 湯気 is the everyday word for visible vapor rising from hot water or food.