The spelling of the word "postfactor" can be explained using IPA phonetic transcription. The first syllable, "post," is pronounced as /poʊst/, with a long o sound and a voiced consonant "s." The second syllable, "factor," is pronounced as /fæktər/, with a short a sound, the "ct" consonant cluster, and a neutral vowel schwa at the end. Together, the word means "something that is introduced or occurs after the fact." This spelling remains consistent with the rules of English phonetics.