Antonyms for the word "served the purpose" could include failed to meet expectations, ineffective, useless, pointless, nonfunctional, inadequate, flawed, unsuitable, or inappropriate. These antonyms suggest that something did not achieve what it was intended to do or did not deliver the desired outcome. For instance, if a product "failed to meet expectations," it means the product did not perform as well as it was expected to. Similarly, if something is "useless," it means it has no use at all. Antonyms like "ineffective" or "nonfunctional" refer to how something does not work properly or cannot accomplish any meaningful results.