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Consider it done:
Firstly ask the question to each of them, "are you the random one?" this will always get either 2 yes's and a no, or 2 no's and a yes 'cos the liar will always reply yes and the truth-teller will always reply no, with the random one saying either yes or no.
We don't know which word means what but whichever answer is only given once, we know that he can't be the random one - we just don't know yet whether he is the liar or the truth-teller, so we now ask this one a question that he must answer no to - the question is, "are you the liar?". The truth-teller will reply no to this and the liar will reply no to this. So whatever word he replies with - this translates as "no". Now look at the answer that he gave to the first question. If he replied with the same word, then he said no to the first question so he must be the truth-teller. If he replied with a different word, then that word must mean yes and he must be the liar. So we now know the translation of the words and we have the identity of either the liar or the truth-teller (depending on what answers were given). Lastly, ask the truth-teller/liar, whilst pointing to one of the other 2 men, "is that the random one?" You can deduce the final identities, as you know the identity of the one you're asking the question to.