water vapor; steam
Refers to water in its gaseous state, especially when invisible or mixed with air. In everyday use, it can also refer to visible steam, though 湯気 is more common for visible steam from hot water.
Water vapor in the air cools and turns into water droplets.
Steam is rising from the kettle.
Water turns into vapor when heated.
Summer air contains a lot of water vapor.
When you boil water, water vapor is generated.
The water vapor condensed on the cold window glass into droplets.