Romanization systems for Chinese vary, but all have the issue that a single "word" in the romanized system can map to dozens, if not hundreds, of actual "words" in the target language.

Pinyin is sort of the standard for romanization, although other systems exist, as well as inputs that aren't based on romanization (bopomofo).

Take the pinyin `fei`. Just looking at the tones that can be on this word, it can mean at least 4 words (my dictionary app couldn't find any neutral tone words). In reality, its at least dozens, each with different contextual meanings.