The word "FIRSV" does not have a recognized spelling in the English language. However, through the use of the International Phonetic Alphabet (IPA), we can break down the sounds that make up this word. "F" represents the voiceless labiodental fricative [f], "I" represents the vowel sound [ɪ], "R" represents the alveolar approximant [ɹ], "S" represents the voiceless alveolar sibilant [s], and "V" represents the voiced labiodental fricative [v]. Therefore, the correct spelling would be "FIRSUV" or "FIRSOF."