Iguassu is a proper noun that refers to a spectacular waterfall located between Brazil and Argentina. There are several synonyms that can be used to refer to this famous natural wonder. One of the most common synonyms is "Iguazu," which is a Portuguese spelling of the word. Another synonym is "Iguacu," which is a Spanish spelling of the word. Other synonyms include "Cataratas do Iguassu" (which is the waterfalls' Portuguese name), "Las Cataratas del Iguazu" (which is the waterfalls' Spanish name), and "Iguassu Falls." Regardless of which synonym is used, it is clear that Iguassu is a breathtaking natural wonder that is worth visiting.