We must also acknowledge, based of his ability to communicate with English, combined with a copy pasted response from a Google search... that the probability of him ever having prior knowledge of the word was zero.
Edit: being that he seems to be waiting up on me to "figure it out." He is due a response.
I believe you took an opportunity to expand your very weak vocabulary by making an ill thought assumption that nemesis is a moron. If i had to take a rough educated guess as to what his I.Q. is compared to yours, id say he is sitting in the 110-120's while you linger around something just shy of rock.