There is no way to answer this question, because to answer it you have to count the words in each language and then compare those numbers.
However there are problems with both parts of this -- with counting and with comparing.
Counting: In almost every language there are base forms that can be inflected, declined, and suffixed/prefixed any number of ways (for example: press, pressing, pressed, depressed, repressed, suppressed, oppressed, impress, etc) and many languages, like German, allow speakers to make new words by combining existing words. On top of that, speakers of living languages constantly add new words to the language by invention and by borrowing, and older words fall out of regular usage. So... how do you go about counting? It is just not possible make an accurate count.
Comparing: There are about 6500 languages in the world, but few of them have dictionaries of high quality like, for instance, the Oxford English Dictionary. So even if you wanted to make an approximation by looking at how many words are in the best dictionaries, this effort will fail. You can't compare if you don't have similar things to compare!
It is widely assumed that English has the most words, but even the Oxford English Dictionary editors say that this claim cannot be supported. Arguments can be made that other languages, like Indonesian/Malay or Finnish, may have as many or more words than English
Appendix:
Hungarian, can also easily be the answer, with more than one MILLION distinct words, of which 100.000+ are used in DAILY conversation today and ALL of the rest can be understood by today's erudite speakers.
Hungarian is a very old and unique language, with no language family relatioships (sorry uralic languages, bye-bye) and more than 30% of the words being untraceable into any other language and more than 20% untranslatable.
English
I do.
The English language.
The most common words in any language are typically short, everyday words like "the," "and," "is," "it," and "you." These words are used frequently in speech and writing, making them essential for communication.
The language with the most words is English, with over 1 million words. However, the average native English speaker knows around 20,000 to 35,000 words.
Penguin.
Some of the most commonly used words in the English language include "the", "people", "about", and "like". Other words include "time", "because", and "first".
sight words are the most common words in the English language
English is often considered to have one of the largest vocabularies of any language, with over 1 million words.
English is often considered to have one of the largest vocabularies of any language, with over 1 million words.
There are words that considered hight frequency words in every language. In English, some of those words are, I,see, me , my, they, can, have. Each language will have their own 100 top words.
There are over 270,000 words in the Italian language, making it one of the richest and most expressive languages in the world.