The correct spelling of the word "Hynum" is actually "Hinein", which is a German word meaning "inside" or "inward". The IPA phonetic transcription of "Hinein" is /hɪˈnaɪn/. The reason for the discrepancy in spelling could be due to a variety of factors, such as mishearing the word or attempting to spell it phonetically in English. Nevertheless, it is essential to use the correct spelling and IPA transcription to ensure proper communication and understanding.