To an extremely high degree; much more than usual or expected.
From 'exceed' (Latin 'excedere'—'ex' + 'cedere,' to go beyond) plus the adverb suffix '-ingly.' Standard usage emerged in the 14th century.
Exceedingly appears constantly in older literature because it expressed intensity before modern intensifiers like 'very' or 'really'—tracking word choice shows how each era dramatizes emotion differently.
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