[dsr_]

Googling says that Shakespeare used 31534 words , of which 14376 appear only once, 4343 twice: http://biomet.oxfordjournals.org/content/63/3/435.abstract

Not a modern corpus, but reasonable.

Strong's Exhaustive Concordance of the Bible (that would be the King James version) lists 8674 Hebrew root words for the pentateuch, and 5624 Greek root words for the New Testament.

Wikipedia suggests that full literacy in Chinese requires knowledge of about 4000 characters.

[akavi]

Note that in Chinese, character is not the same as word.

Most modern Mandarin words are bisyllabic, and represented by the combination of two characters, and their meaning does not necessarily derive in a straightforward way from the meanings of their constituent characters (for example, the word for "thing" is composed of the characters for "East" and "West" in conjunction)

[lurker14]

Of those unique words, how many did Shakespear invent?

Making up new words is an easy way to boost vocabulary.