1. a device or system that removes condensation or mist from a surface, especially a car windshield or mirror
Usage: common in automotive contexts; British English term; American English often uses 'defroster'

Examples

• Turn on the demister to clear the windshield on this foggy morning.
• The car's demister quickly removed the condensation from the windows.
• She switched on the rear demister to defog the back window.
• Modern vehicles have automatic demisters that activate when moisture is detected.
• The bathroom mirror has a built-in demister to prevent fogging after showers.