Thank you, sir, for this detailed reply. It's really useful, especially these parts about 'mental meaning'(each man have his own mental picture of the word dog') and about descriptions in the new language. Yes, oxford's dictionary of synonyms is enough for practicing English. And of course, personal communication is the key. But some times it is very difficult to pass trough a communication border. For example, I have many Nepali friends who speaks some subset of English (very similar to that I'm speaking) but it's impossible for me to start learning Nepali language from them, because of limitedness of our English.