Goniff is a Yiddish word that refers to a thief or a swindler. However, there are several synonyms that can be used in place of goniff, depending on the context and severity of the person's actions. These synonyms include thief, burglar, robber, crook, fraudster, con artist, embezzler and pickpocket. In some cases, one may also use terms like scammer, grifter or hustler to describe a goniff. Regardless of the word used to describe a thief or swindler, it's important to remember that their actions are harmful and illegal, and they should be reported to the authorities.