"Hoi" is a term originating from the Dutch language, commonly used as a casual greeting similar to "hello" or "hi". While it may not have many synonyms in the English language that specifically match its casual tone, there are alternative phrases that could convey a similar meaning. Some synonyms for "hoi" could include "hey", "howdy", "what's up", "g'day", "hiya" or "yo". These words capture the informal and friendly nature of "hoi" and can be used interchangeably depending on the context. Regardless of the synonym used, all these words serve the purpose of initiating a casual conversation or greeting someone in a friendly manner.