The syllable of "tian" in English is typically pronounced as "tee-an." This pronunciation reflects the two-syllable structure of the word, with "tee" representing the first syllable and "an" representing the second. The division of the word into syllables is based on the phonetic rules of English, which dictate that a syllable generally consists of a vowel sound, often accompanied by a preceding consonant cluster.

The reason for this pronunciation can be attributed to the phonological adaptation of Chinese words when they are borrowed into English. Chinese characters often correspond to syllables, and when these syllables are adopted into English, they are typically pronounced according to English phonetic conventions. In the case of "tian," the Chinese character 天 corresponds to the syllable "tian," which is then adapted to the English phonetic system. The "t" in "tee" is a result of the English consonant "t," while the "an" represents the vowel sound in "tian," which is pronounced as "ee" in English.

Data supporting this analysis can be found in phonetic dictionaries and linguistic studies on loanwords. For instance, the Oxford English Dictionary (OED) lists "tian" as a borrowed word from Chinese, with its pronunciation given as "tee-an." Similarly, linguistic research on Chinese-English loanwords often discusses the phonetic adaptation process, highlighting the transformation of Chinese syllables into English syllables. This adaptation is a common feature in the integration of foreign words into the English language, where the phonetic structure of the source language is often modified to fit the phonetic rules of the receiving language.