Looking unhealthy, pale, or sickly, or resembling a peak or pointed shape.
From 'peak,' suggesting someone is thin or pointed like a peak, or peaked with illness. British English usage mainly refers to appearing ill, from 19th-century dialect.
This word perfectly captures that Victorian concern about looking 'peaked'—back then, pale and thin meant you'd been studying too hard or fighting disease, which doctors actually took seriously.
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