The spelling of the word "Vernonin" can be explained using the International Phonetic Alphabet (IPA). The first syllable, "Ver", is pronounced as /vɜːr/, with the "e" sound as in "her" and a stress on the first syllable. The second syllable, "non", is pronounced as /nɒn/, with a short "o" sound as in "lot". The final syllable, "in", is pronounced as /ɪn/, with a short "i" sound as in "sit". Therefore, the correct spelling of this word is "Vernonin."