When looking for synonyms for the word "swiftlier," there are many options to choose from. Some common options may include faster, quicker, speedier, hurriedly, rapidly, expeditiously, accelerated, and briskly. Additionally, some more specific options may include fleetly, hastily, promptly, hastily, hurriedly, and expeditiously. Each of these synonyms carries its own unique connotations and nuances, and may be more or less appropriate depending on the context and tone of the sentence. Regardless of the specific synonym chosen, all of these options convey a sense of quick and efficient movement or action.