The spelling of the word "unfaithfuls" can be explained through its IPA phonetic transcription. The first syllable is pronounced as "ʌn" to indicate negation, followed by "feɪθ" to convey the meaning of faithlessness. The final syllable is pronounced as "fʊlz," indicating multiple persons. Therefore, "unfaithfuls" is spelled to indicate a group of people who are lacking in loyalty or trustworthiness. The spelling reflects the English language's conventions on pluralization and is commonly used in literature and conversations to describe such individuals.