The term "diselenious acid di Na salt of Sodium Selenite" is quite complex, but it represents a specific compound within the field of chemistry. Synonyms for this compound can be challenging to come by, as it is a specialized term. However, some possible alternatives may include "selenium salt", "di-sodium selenite" or "Na2SeO3". These terms, while not exact equivalents, help describe similar concepts within the realm of chemical compounds. It's important to note that in scientific contexts, specific terminology is crucial to ensure accurate communication and to adhere to standardized nomenclature.