Cnoidal is an adjective that describes a particular type of wave shape, which is similar to that of a sine wave or cosine. However, there are other terms that can be used as synonyms for this word when describing different types of waves. For example, "stokes" waves are similar to cnoidal waves, but they have a flatter profile and move slower. "Solitons" are another type of wave that can be used synonymously with cnoidal waves, but they are solitary waves that propagate without changing shape. Other synonyms for cnoidal waves include "periodic" waves, "oceanic" waves, and "wave trains." Ultimately, the choice of synonym will depend on the specific type of wave being discussed.