IH is not a word recognized in the English language. Therefore, there are no synonyms for this word. Perhaps, you meant to type "HI," which is a common greeting. Some synonyms for "HI" include hello, hey, greetings, salutations, and hiya. These words are some of the more informal and casual ways to greet someone. There are also more formal greetings, like Good morning, Good afternoon, and Good evening. These formal greetings are commonly used in professional settings. Regardless of the greeting used, it's always important to be respectful and courteous when greeting someone.