The spelling of the word "fassi" can be explained using the International Phonetic Alphabet (IPA). The first two letters "fa" are pronounced as "fæ" with a short "a" sound. The following "s" is pronounced as "s" with a hissing sound. Finally, the last two letters "si" are pronounced as "si" with a long "ee" sound. Therefore, "fassi" is pronounced as "fæsiː". This spelling and pronunciation guide can be helpful in understanding the proper usage of the word.