There are many synonyms for the phrase "fleet of foot," which refers to someone who is fast or nimble. Some common alternatives include "swift," "agile," "light-footed," "quick," "speedy," "sprightly," "lively," "athletic," "dextrous," and "lithe." These words all convey a sense of physical prowess and speed, and are often used to describe athletes or individuals with exceptional physical abilities. Another related term is "fleetness," which can refer to both speed and agility. Overall, there are many ways to describe someone who is "fleet of foot," depending on the specific context and intended meaning.