This word developed from “felicity,” which comes from the Latin root “felic-,” meaning “happy.” While the adjective “felicitous” today can describe something that turns out to be a lucky or opportune occurrence, it’s rooted in the sense that it makes someone happy. To be a truly felicitous occurrence, it should be lucky and make someone happy — such as finding your lost set of keys in time to make a friend’s surprise birthday party. Can you have a lucky day that doesn’t make you happy? Maybe you get a surprise flight upgrade, but your traveling partner is still stuck in coach. That might not be a felicitous occasion, but we’ll let you be the judge.