To cause something to lose focus or become blurred; to move out of focus.
From de- (away from) + focus (point of concentration, literally 'hearth' in Latin). Focus comes from Latin focus meaning 'fireplace,' which became the 'point where rays meet,' and metaphorically 'center of attention.'
The word 'focus' itself comes from Latin for 'fireplace'—originally, optical scientists used the image of rays converging at the hearth to explain how light concentrates at a single point, one of the best examples of how metaphor builds scientific language.
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