'acarus' originates from Greek, specifically the word 'akari', where 'a-' meant 'not' and 'karos' meant 'heavy sleep', referring to the small size and activity of mites.

'akari' transformed into the Latin word 'acarus', and eventually became the modern English word 'acarus'.

Initially, it referred to any small insect, but over time it evolved into its current meaning of a specific genus of mites.