It could be:
* A misspelling: It might be a typo for "him" or "high."
* A slang term: It might be a slang word or regional dialect term with a specific meaning, but without more context, it's impossible to know.
* A name: It could be a person's name.
Could you please provide more context about where you encountered the word "hiam"? This will help me understand what it might mean.