I am a mobile programmer and I want to create a mobile app to learn English. One part of this app contains a list of movies and under each movie you can find the difficult words mentioned in that movie and the translation to another language, so the students can study them before watching the movie.
Is this legal or not?
Note: this app does not contain the movie itself. It just contains the words and translation.
It depends on how much you "copy" (including translate). If you were to have a list of 250 or even 1000 challenging words that appear in the movie, and even list the words in the order that they first appear in the movie, then there is no question of infringing on their copyright. If you create a transcription or translation of any part of the movie, then you are potentially infringing (a transcription being where you write down the spoken English dialogue). There are circumstances, pertaining to "fair use", whereby you could defend yourself in a lawsuit, but you would really need to engage a copyright attorney to advise you where the limit is. The purpose of the "fair use" defense is to make it possible for someone writing a review of a movie to actually quote short bits of dialogue. From the perspective of what would be useful for language learning (i.e. the amount of text that you would need to copy), providing a translation would almost certainly constitute infringement.
In listing words which occur in a movie, you would not need to limit yourself to just single words, because there are idiomatic expressions like "down with that" or "kick the bucket", which involve a number of words but function as single units. When it comes to text, the copyright holder does not own the specific words, but he owns the "expression". The closer your product is to replicating that text, the more likely it is that the product will be found to infringe (this is why my example involved just listing the words once: and it should not be the 25,000 most difficult words, since that would amount to near-literal copying for a substantial initial part of the movie).
If the movie is also released with e.g. Arabic subtitles (which would involve a licensing agreement), then greater caution would be advised in providing a word-list of difficult words that appear in the movie, because of the "effect on market" consideration.
IANAL
My personal reading of copyright law is that it would be fair use as you are not, in any way breaching their copyright. Assuming you still need the original work, which you are not supplying, to gain any understanding of the work.
Example; for the song Supercalifragilisticexpialidocious from the Mary Poppins film I could define the following words
Supercalifragilisticexpialidocious
atrocious
precocious
tweak
cat has got your tongue
but it does not give you any understanding or context of the song.
