Is a vassal like a quarry?

Today in my French history, my professor was talking about the Franco-Prussian War (all in French), and used the word vassal. He then tried to explain the definition of the word in French, but he was having a lot of difficulty giving the meaning. But he didn't have to because someone in the class spoke up and said, its the same word in English. Everyone nodded in agreement to him. I said to the person next to me, I've never heard that word in my life. The whole class turns around and stares. Ok, didn't mean to say it that loud. Someone responded, you can just look it up in the English dictionary. I just respond to the class, oh right, I know it, just kidding...

So, I am just wondering, is vassal one of those words like quarry? (Connection back to the concentration camp we visited earlier on in the trip, where the prisoners worked on a quarry, and I had never heard of it.) I am convinced that at some point in my life I missed out on all of these lessons of words that everyone else knows. For some reason, I missed the quarry lesson, the vassal lesson, what else is there? I know that there will be some other word that comes along while in France where I will be the only one who doesn't know. I feel like this would just happen to me. Even in France.


For those of you who want to know: A vassal is "a person granted the use of land, in return for rendering homage, fealty, and usually military service or its equivalent to a lord or other superior; feudal tenant."
Cite: dictionary.com