The phrase "hath to dinner" is an archaic term that means "has to go to dinner." Instead of using this outdated expression, there are plenty of synonyms that can be used in modern language. Some options include "needs to dine," "must have supper," "has dinner plans," "requires sustenance," or simply "is going to eat." These variations convey the same meaning as "hath to dinner," but in a more contemporary and understandable manner. It's essential to choose the right words when communicating to ensure clear and effective communication.