Superlative form of damned; most extreme, surprising, or difficult; often used in phrases like 'the damnedest thing' to express amazement.
From damn plus -ed suffix plus -est (superlative). Damn comes from Latin damnare meaning 'to condemn.' The superlative form intensifies the sense of extremity or intensity.
The damnedest thing about 'damnedest' is that it's actually pretty mild now—it started as actual religious swearing but became so overused that it lost its power to offend and became almost affectionate when people say 'Well, that's the damnedest thing!'
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