In a manner that is bounded by or composed of curved lines; in a curved or flowing way.
From 'curvilinear' plus the adverbial suffix '-ly'. The adverbial form enabled technical writers to describe processes or arrangements that follow curved patterns.
When physicists say light bends 'curvilinearly' around a massive object like the sun, they're describing one of the mind-bending predictions of Einstein's relativity theory.
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