Maciamo said:
English has 500.000 words or 2 million if you include technical term. That is much more than the average of European languages, with French having barely 70.000 words and German 120.000.
It seems generally agreed that English has the most words in the world, though I doubt that the difference is as great as given here.
The problem with all this is, what you can count as a word, how "word" is defined. Defined as "basic morpheme", estimations go to around 5000 (plus loanwords) for German. Do you count active vocabulary only or passive vocabulary, the 1st is maybe a few thousand while the latter is estimated between 12,000 & 100,000. Do you count inflected words? Do you count words or meanings? When are loanwords part of the language, should they be counted at all? Do you count what's in a dictionary, then which dictionary to go for?
Here's a small list of German dictionaries:
Duden, 1. Auflage (1880): 27000
Duden, 22. Auflage (2000): 120000
Wahrig, 7. Auflage (2000): 250000
Grimmsches W?rterbuch (1838?1961): 350000
Mackensen (1977): 170000
Wahrig in sechs B?nden (1980?1984): 220000
Duden in zehn B?nden (1999): 200000
for comparison:
Webster's Collegiate (1993): 160000
Webster's Third (1961): 450000
Oxford English Dictionary (1989): 290500
As you see, all vary widely, not only the German ones. Interesting to note that Wahrig in six books has less words counted than the Wahrig 2000 in one book.
The project to build an electronic database with a "complete" German vocabulary (full forms, with inflected words et al.) based on factual usage is at 5 million words at the moment. By far not finished.
All what was written above is probably similar in all major living languages.
The dictionary list is taken from
http://faql.de/sonstiges.html#wortschatz
It's German, but I think you can understand German, so it should be interesting for you, Maciamo.
A similar text on the futility of counting words, in English:
http://www.sls.lib.il.us/reference/por/features/97/language.html