I agree though that whatever found here and there is only as good as it gets, but it might be enough of a starter.
Here e.g. should be a number of english dictionaries, copyright status better don't ask.
Just looking, I found
a severe critic of the Doug Harper one. Haven't read the paper in depth, skimming it I think it says "he just abridged the Oxford dictionary" and "he is baloney on Arabic". Can't really say.