Words are the smallest clause constituents. There are three points to consider when judging whether a unit is a word or not.
First, a monosyllabic form can be taken as a word if it can be used independently and if it expresses a substantial lexical meaning. For example, in hěn hǎo both hěn (‘very’) and hǎo (‘good’) are words. As another example, the two syllables miǎn and tiǎn are not meaningful when they are separated; they are not words. Their combination in that order, miǎntiǎn , means ‘shy’; they form a bisyllabic word.