While he was known for his imaginative language and unique wordplay, most of the "new" words he used were actually:
* Existing words used in a new and unusual way: This is called neologism. For example, "snozzcumbers" (a fictional fruit) combines "snot" and "cucumber" to create a humorous image.
* Portmanteaus: These are words made by combining parts of other words. Examples include "Oompa Loompas" and "Gobblefunk."
While it's difficult to count these, Dahl's use of language was so inventive that it's safe to say he significantly enriched the English language in a playful and memorable way.