Producing profit, income, or advantage; employed or working in a way that earns money, especially as in 'gainful employment.'
From 'gain' plus the suffix '-ful' (full of, characterized by), from Old English '-full.' The combination creates an adjective meaning profitable or productive.
'Gainful employment' is a phrase that never dies in legal and official documents—it reveals how societies measure a person's value by whether they're earning money, which is a pretty recent and Western-specific idea historically.
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