The phrase "orb of day" is a somewhat archaic way of referring to the sun. However, there are several synonyms that can be used to describe the same celestial body. For instance, "sol" is a Latin term that means "sun" and can be used as a synonym. "Helios" is another ancient Greek name for the sun. "Star" can also be used to refer to the sun, as it is technically a star that is closest to Earth. Another option is "light-giver," which refers to the sun's role in giving light and warmth to our planet. Ultimately, there are many ways to describe the "orb of day," each with their own unique connotations and origins.