Lets say we have a word with $n$ letters, if we then assign a number like above to each of the letters in the word, say $a_1, a_2, \ldots, a_n$. We then generate the polynomial $$f(X) = a_1 \cdot X^{n-1} + a_2 \cdot X^{n-1} + \ldots + a_{n-1} \cdot X^1 + a_{n}.$$ What we have done now is encode a word into a polynomial!

Suddenly Dr. Evil has kidnapped $2$ of your $3$ friends because he wants to know you secret word. But you don't have to worry (except for your friends) because Dr. Evil will never be able to uniquely determine all the coefficients in your polynomial because of the way equations with multiple variables work.