1. a substance in gaseous form, especially water when suspended in air
2. a barely visible or cloudy diffused matter suspended in air

1. to rise or pass off in vapor

Examples

• Water vapor rose from the hot pavement after the rain.
• The morning mist was just water vapor hanging in the cool air.
• You could see vapor coming from his breath in the cold weather.
• The scientist studied how liquids vapor at different temperatures.
• Steam is water vapor that becomes visible when it cools.
• The vapor from the hot soup fogged up her glasses.
• Chemical vapors filled the laboratory during the experiment.