To delay or slow down the progress of something. In technical contexts, it means to make something happen later or slower than expected.
From French 'retarder,' from Latin 'retardare' (re- 'back' + tardus 'slow'). The word originally meant simply 'to make slow' or 'to delay,' and this remains its primary definition in technical and formal contexts.
While this word has a legitimate technical meaning (engine ignition timing can be retarded), the slur usage is so dominant now that the original meaning is rarely used—a powerful example of how a word's harmful meaning can overshadow its innocent origins.
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