* No single definitive dictionary: There are many different online dictionaries, each with its own criteria for inclusion. Some prioritize common words, others include more obscure terms, and some may focus on specific fields or languages.
* Constantly evolving: Dictionaries are constantly updated with new words, slang terms, and technical vocabulary. The number of words in a dictionary is always changing.
* What counts as a "word"? The definition of a "word" itself can be subjective. Does it include proper nouns? Technical terms? Different dictionaries handle these nuances differently.
That being said, some online dictionaries have estimated numbers:
* Merriam-Webster: Claims to have over 470,000 words.
* Oxford English Dictionary: Has over 600,000 words, but this includes historical words and variants.
It's best to think of these figures as rough estimates. The specific number of words in an online dictionary will vary depending on the dictionary and its criteria.