When something is "not to the purpose," it means it's irrelevant or doesn't serve the intended goal. There are many synonyms to describe this, such as off-topic, beside the point, tangential, extraneous, nonessential, unimportant, inconsequential, immaterial, insignificant, and useless. All of these words describe something that doesn't contribute to the main objective or issue at hand. It's important to use words like these when you're communicating in order to stay focused and ensure your message is clear. Whether you're writing an email, essay, or speech, incorporating these synonyms can help you avoid confusion and enhance your effectiveness as a communicator.