Written Chinese
Because the majority of modern Chinese words contain more than one character, there are at least two measuring sticks for Chinese literacy: the number of characters known, and the number of words known. John DeFrancis, in the introduction to his "Advanced Chinese Reader", estimates that a typical Chinese college graduate recognizes 4,000 to 5,000 characters, and 40,000 to 60,000 words. Jerry Norman, in "Chinese", places the number of characters somewhat lower, at 3,000 to 4,000. These counts are complicated by the tangled development of Chinese characters. In many cases, a single character came to be written in multiple ways. This development was restrained to an extent by the standardization of the seal script during the Qin dynasty, but soon started again. Although the "Shuowen Jiezi" lists 10,516 characters—9,353 of them unique (some of which may already have been out of use by the time it was compiled) plus 1,163 graphic variants—the "Jiyun" of the Northern Song Dynasty, compiled less than a thousand years later in 1039, contains 53,525 characters, most of them graphic variants.
Chinese characters
When the script was first used in the late 2nd millennium BC, words of Old Chinese were generally monosyllabic, and each character denoted a single word.
Increasing numbers of polysyllabic words have entered the language from the Western Zhou period to the present day.
It is estimated that about 25–30% of the vocabulary of classic texts from the Warring States period was polysyllabic, though these words were used far less commonly than monosyllables, which accounted for 80–90% of occurrences in these texts.
The process has accelerated over the centuries as phonetic change has increased the number of homophones.
It has been estimated that over two thirds of the 3,000 most common words in modern Standard Chinese are polysyllables, the vast majority of those being disyllables.