English is an expansive language, anyone who has seen the size of an unabridged English dictionary can tell you that. It's also a language that's ever changing and evolving, so of course there are some words that fall out of favor and are hardly ever used, but maybe it's time to bring some of them back!
It comes from the Greek word εὔνοια, meaning "well mind" or "beautiful thinking. Eunoia is the shortest English word containing all five main vowel graphemes. In book eight of Nicomachean Ethics, Aristotle uses the term to refer to the kind and benevolent feelings of goodwill a spouse has which form the basis for the ethical foundation of human life.