The spelling of the word "apyonin" can be explained using the International Phonetic Alphabet (IPA). The first syllable, "ap," is pronounced with an open front unrounded vowel (æ) and a voiceless bilabial stop (p). The second syllable, "yo," is pronounced with an open-mid back rounded vowel (ɔ) and a voiced palatal approximant (j). The final syllable, "nin," is pronounced with an open front unrounded vowel (æ) and a voiced alveolar nasal (n). The spelling of "apyonin" accurately reflects its phonetic pronunciation.
Pyoktanin yellow.
A practical medical dictionary. By Stedman, Thomas Lathrop. Published 1920.