When something has outlived its usefulness or relevance, it becomes obsolete. However, there are several other synonyms for this phrase that you can use to make your writing more interesting, such as outdated, archaic, outdated, superseded, antiquated and old-fashioned. Each of these synonyms conveys a slightly different nuance, so selecting the most appropriate one will depend on the context and tone you want to achieve. For example, outdated might suggest something that is no longer current but still has some historical significance. On the other hand, archaic conveys a sense of being outdated to the point of being ancient. Overall, when it comes to using synonyms for becomes obsolete, there are plenty of options to choose from, allowing writers to add variety and depth to their writing.