immiscible?

When I got home yesterday, my father asked me if I knew the word, "immiscible." He told me about my 10-year old cousin who gave him an idea of such word. My cousin said, "oil and water are immiscible or can't be mixed." Honestly, the word was strange to me and I can't recall that it was taught in any of my Science classes. Then I hastily searched through Google and found out that it does exist. With amazement, I just praised my cousin for introducing a new word to us.