* Different dictionaries have different criteria: Some dictionaries include technical terms, slang, and proper nouns, while others focus on common usage.
* The language is constantly evolving: New words are created, and old words fall out of use.
* There's no single authoritative source: There's no central organization that dictates what's considered a "real" word.
However, here are some estimations:
* The Oxford English Dictionary (OED): A comprehensive dictionary, it includes over 600,000 entries and defines over 200,000 words.
* Merriam-Webster: A popular dictionary, it claims to include over 470,000 words.
Ultimately, the number of words in the English dictionary is a constantly changing and imprecise figure.