In a generous or plentiful way; more than enough.
From 'ample' (Latin 'amplus' meaning 'large, spacious') plus adverbial suffix '-ly'. The root suggests something physically spacious that became metaphorically generous.
The Latin word 'amplus' originally described wide, spacious places—so when we say something is done 'amply' we're using an old geography word to describe abundance, showing how abstract language grows from physical space.
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