The phrase "most ex" could be a short form for many different words, but the most commonly used meaning of it is "most excellent" or "most exceptional." Some synonyms for "most excellent" might include superb, outstanding, first-rate, top-notch, and exceptional. Other synonyms might include "most expensive" or "most exclusive," which could include terms such as deluxe, luxurious, high-end, premium, and elegant. All of these synonyms convey a sense of being the best, the most superior or the most exclusive in their respective fields, making them perfect for those who want to describe something that is truly exceptional or remarkable.