The spelling of the name "Thompkins" is determined by its pronunciation. In IPA phonetic transcription, it is written as /ˈtɑːmpkɪnz/. The first syllable is pronounced with a long "ah" sound, followed by a short "m" sound. The second syllable is pronounced with a short "ih" sound and is followed by a velar nasal "ng" sound. The final syllable has a short "ih" sound, followed by a voiceless alveolar plosive "t" sound and a voiced alveolar nasal "n" sound. This helps in correctly spelling the name "Thompkins".