Let's say carrot for a shade of orange.
Suppose carrot is not used for the color and I wanted one to describe the vegetable's color. So, I revive the displaced more for the color. What do you call such revival?
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Although carrot is not an obsolete word, what is being described here is a metonym. It does not matter if the word is obsolete or not. If you need a word for something new and you repurpose an existing word it is a metonym. This is different from a metaphor where the word is used to describe the new thing with the old meaning. These are so confusing than Wikipedia has an article on this specific issue.
Computing provides some examples of obsolete, or at least obscure, words being used as metonyms, such as sprite, gremlin and bus. This last is of course still in use, but not in the sense that led to its use in computing.