'hoarfrost' originates from Old English, specifically the word 'hār,' where 'hār' meant 'gray, venerable, old.'

'hār' changed from Old English word 'hār' and eventually became the modern English word 'hoarfrost'.

Initially, it meant 'gray or venerable frost,' but over time it evolved into its current meaning of 'white frost formed by freezing dew or vapor.'