earn: [OE] The underlying sense of earn is ‘gain as a result of one’s labour’. It comes from a prehistoric West Germanic verb *aznōjan, which was based on the noun *aznu ‘work, labour’. This seems often to have been used specifically for ‘work in the fields’, for several other related forms in the Germanic languages, such as German ernte and Gothic asans, denote ‘harvest’, which in some cases has been metaphorically extended to apply to ‘autumn’. [earn etymology, earn origin, 英语词源]