The Chinese word 尼古丁 is formed through phonetic transliteration, where each character is selected to mimic the sound of the corresponding syllable in the English word "nicotine": "尼" (ní) for "ni", "古" (gǔ) for "co", and "丁" (dīng) for "tine". The characters are used solely for their sound values and do not convey meaning related to the substance.