The phrase "most bulbous" can be replaced by several synonyms depending on the context. For instance, "most protuberant" is a synonym that describes something that bulges out prominently. "Most spherical" is another synonym that characterizes something that has a well-rounded shape. "Most rounded" or "most curvaceous" might also be appropriate synonyms if describing something with a smooth, plump appearance. "Most swollen" is another term that could be used, especially if describing something that is enlarged due to inflammation or fluid retention. Ultimately, there are several words that can substitute for "most bulbous," and their use depends on the specific context and desired connotation.