Past tense of foil; prevented someone from accomplishing something, especially by clever or determined action; thwarted.
From Old French fouler meaning 'to trample, crush,' which evolved to mean defeating or frustrating plans. The sense of 'thwarting' emerged in the 16th century, separate from the metallic 'foil' which comes from Latin folium 'leaf.'
The verb 'foil' meaning to thwart comes from an entirely different source than foil the thin metal - they're linguistic twins that just happen to share the same spelling. This is called homonymy, where unrelated words converge on identical forms through historical accident.
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