A compound of light + bar
Proto-Indo-European *lewk- ‘to shine’
…
Proto-Germanic *leuhtą
Proto-West Germanic *leuht ‘light’
Old English lēoht
Middle English light ‘light, illumination’
English light
Vulgar Latin *barra
Old French barre ‘beam, bar, gate, barrier’
Middle English barre
English bar
Today it means
noun A bar mounted on the roof of a vehicle, such as a police car, with rotating beacons or other lights to provide a visual warning.
Language periods are conventional ranges, not dates for this word.
Etymograph / lightbar
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