It's like with Kolmogorov complexity. The upper bound is translation from "word_x" into "book in your language that teaches you the other language and then says

It's like with Kolmogorov complexity. The upper bound is translation from "word_x" into "book in your language that teaches you the other language and then says 'word_x'". But just like Kolmogorov complexity the fact that you can technically translate anything and the change in length is finite - doesn't mean it's irrelevant in practice.