What does defroster mean?
A defroster is a mechanical or electrical device designed to remove frost, ice, or condensation from glass surfaces, most commonly the windscreen or windows of a vehicle. Typically operated by directing warm air across the glass — either through dashboard vents for the front windscreen or via embedded heating elements for the rear window — the defroster restores visibility quickly and safely in cold or humid conditions. The term is firmly rooted in automotive vocabulary and is the standard expression in American English, where drivers routinely speak of turning on the front or rear defroster on icy mornings. British speakers are more likely to say 'demister', though 'defroster' is widely understood. Beyond cars, the word occasionally appears in domestic contexts, such as the defrost function of a microwave oven. Practical and unambiguous, 'defroster' belongs to the everyday language of driving and weather, useful whenever visibility is compromised by frozen or misted glass.
nounA device, especially in a vehicle, that removes frost or condensation from a windscreen or window by blowing warm air over it.
- A device in vehicles that blows warm air onto windows to clear frost or condensation.
- Any appliance or device used to thaw frozen items (e.g., a microwave defroster setting).
"She switched on the rear-window defroster and waited for the ice to melt."
"On cold mornings he starts the car early so the defroster can clear the windshield before his commute."
"Select the defroster setting on the microwave to thaw the chicken evenly."
Regular plural formation. Usually singular when referring to a specific vehicle's own defroster.
"Modern cars come equipped with both front and rear defrosters as standard."
The word 'defroster' only exists because cars needed it — it's one of those rare words invented purely by automotive engineering.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of defroster
'Defroster' derives from the verb 'defrost', formed by adding the prefix 'de-' (indicating removal or reversal) to the Old English noun 'frost', which itself comes from Proto-Germanic *frustaz. The agentive suffix '-er' then produced a noun denoting the thing that performs the action. As an English word, 'defroster' emerged only in the twentieth century, coinciding with the development of heated windscreens in automobiles.
Related word forms
How defroster is actually used
Predominantly used in the context of vehicles. In British English, 'demister' is more idiomatic for clearing interior condensation, though 'defroster' is understood. The word carries no strong register — it's neutral, practical vocabulary.
Easily confused with defroster
Both remove window condensation, but 'defroster' is the standard American term while British English typically uses 'demister'.