'high-income' originates from the combination of 'high' and 'income', where 'high' meant 'great in amount' and 'income' referred to 'money received'.

'high-income' evolved from the Middle English word 'income', which meant 'entrance' or 'arrival', and 'high', which has retained its meaning over time.

Initially, 'income' referred to 'entrance' or 'arrival', but over time it evolved to mean 'money received', leading to the modern usage of 'high-income' as 'earning a large amount of money'.