Acting in a way that prevents or obstructs something; meddling in affairs that are not one's concern. Getting involved where one is not wanted.
From Old French 'entreferir' meaning 'to strike each other', from 'entre-' (between) and 'ferir' (to strike), from Latin 'ferire'. Originally described physical collision, but evolved to mean any kind of obstruction or meddling.
The original meaning of 'interfere' involved horses striking each other's legs while running - a serious problem in racing. This physical collision metaphor perfectly captures what interference feels like: an unwanted collision between separate activities or intentions, whether it's radio waves, personal boundaries, or horse legs.
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