Long-running is a phrase that is commonly used to describe an event, show, or activity that has been ongoing for a significant period of time. However, there are several other synonyms that can be used instead of long-running. Some of the popular synonyms for long-running include "long-lasting", "enduring", "perpetual", "persistent", and "continuing". These words can be used to describe a wide range of ongoing activities such as a long-lasting business, an enduring friendship, a perpetual cycle, a persistent campaign, and a continuing trend. Whether you are writing an essay, a news article or a blog post, these synonyms can be used to add variety and interest to your writing.