The term "dinkum" is an Australian slang term that is widely used to describe something that is genuine, honest, and above board. However, in recent times, the word has been used less frequently, especially in the younger generation. Some of the synonyms for "dinkum" include authentic, truthful, sincere, trustworthy, real, legitimate, and bona fide. Other similar phrases that can be used include "the real deal," "the genuine article," and "the real McCoy." These phrases can be used to describe people, products, or situations that are honest and reliable. In short, "dinkum" is a term that can be replaced with several other phrases that have a similar meaning.