The spelling of the word "arnocrinum" can be explained using the International Phonetic Alphabet (IPA). The first syllable, "ar," is pronounced /ɑr/, like the "ar" in "car." The second syllable, "no," is pronounced /noʊ/, like the "no" in "know." The third syllable, "cri," is pronounced /kraɪ/, like the "cry" in "crybaby." The final syllable, "num," is pronounced /nʌm/, like the "num" in "number." Therefore, the correct spelling of "arnocrinum" reflects its pronunciation using the IPA.