The phrase "out sun" does not have any synonyms as it is not a commonly used phrase or word. However, if we consider the words "out" and "sun" separately, we can come up with several synonyms. For example, "out" can be replaced with "exterior," "outside," or "beyond." Similarly, "sun" can be replaced with "solar," "star," or "daystar." These synonyms can be used in different contexts to convey similar meanings. For instance, if we want to explain that something is visible even in bright sunlight, we could say it is visible beyond the sun.