What does demist mean?
"Demist" is a practical English verb meaning to remove mist or condensation from a glass surface, most often the windscreen or windows of a car. Drivers demist their windscreens by switching on the heater, air conditioning, or a dedicated ventilation setting, which clears the film of moisture that forms when warm, humid air meets cold glass. The word is built transparently from the prefix "de-" plus "mist", and it pairs naturally with automotive vocabulary such as "windscreen", "rear window", and "demister" — the small fan vent or setting designed for exactly this job. Though perfectly intelligible everywhere, "demist" is used chiefly in British English; American drivers tend to say "defog" instead. It carries no emotional connotation, being a plain, functional term of everyday motoring life, but it remains genuinely useful precisely because condensation on glass is such a common and safety-critical nuisance.
verbTo remove mist or condensation from a surface, especially the windscreen or windows of a vehicle.
- To remove mist or condensation from a windscreen or window, typically using a vehicle's heating or ventilation system.
"She waited a few moments for the heater to demist the windscreen before setting off."
"Switch on the blower to demist the rear window before reversing."
"In damp weather it can take several minutes to demist the glass properly."
It's one of those everyday car words Britons use without a second thought — yet Americans usually say "defog" instead, making "demist" a quietly regional word hiding in plain sight on every dashboard.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of demist
"Demist" was formed in modern English by adding the prefix "de-", indicating removal or reversal, to the noun "mist". The noun "mist" itself is an ancient Germanic word, traceable to Old English "mist" and related forms in other Germanic languages. The compound verb arose alongside the development of motor vehicles and their windscreens, when clearing interior condensation became a routine driving task, and it gave rise to the derived noun "demister" for the vent or control that performs it.
Related word forms
How demist is actually used
"Demist" is predominantly British English; American speakers more commonly say "defog" or "defrost" in this context. It is a neutral, practical term used mainly in motoring contexts rather than formal writing.
Easily confused with demist
"Demist" means to clear condensation from a surface, while "demise" is a noun meaning a person's death or the end of something.