The word "most undulant" refers to something that has a continuous and flowing motion, like the waves of the ocean. Synonyms for this phrase include "serpentine," which means to move in a winding or sinuous manner, and "undulating," which means moving in a smooth and wavy fashion. Other synonyms include "rolling," "rippling," and "flowing." All of these words evoke a sense of fluid motion and a sense of gracefulness. When used in a sentence, these synonyms can enhance the description of movement, whether it's describing the motion of hills, water, or even a person's movements.