There are various synonyms that can be used to refer to something that is apparent to the naked eye. One option is the term "visible," which implies that the object or phenomenon can be seen without any additional tools or aids. Another possibility is "obvious," which suggests that the thing in question is clearly apparent and easy to notice. "Evident" is another synonym that can be used to describe something that is apparent to the naked eye, conveying the idea that it is clearly visible or perceivable. Ultimately, the choice of synonym will depend on the specific context and tone of the language being used.