"A mite or tick; specifically (in later use) a mite of the genus Acarus (family Acaridae). Also (in form Acarus): the genus itself", Mid 17th cent.; earliest use found in Samuel Purchas (c1605–1659). From post-classical Latin acarus from ancient Greek ἄκαρι mite from ἀκαρής minute, too short for cutting from ἀ- + καρ-, aorist stem of κείρειν to cut.[acarus etymology, acarus origin, 英语词源]