The spelling of the word "BCDBIN" can be explained using IPA phonetic transcription. The first three letters, "BCD," are pronounced with a voiced stop followed by an unvoiced stop and then a voiced stop. The next two letters, "BI," are pronounced with a long "i" sound. Finally, the last letter, "N," is pronounced with a nasal consonant. Together, these sounds form the unique spelling of "BCDBIN". However, it should be noted that this word does not have any known meaning or usage in English language.