non-euclidean adjective, often capitalized E non-eu·clid·e·an \ ˌnän-yü-ˈkli-dē-ən \ Trending Now: More Trending: lowlife kakistocracy slimeball salacious oligarch SEE ALL See What's Trending Now See More Trending Words What's Trending Now More Trending Words lowlife 'a person of low moral character' kakistocracy 'government by the worst people' slimeball 'a morally repulsive or odious person' salacious 'arousing or appealing to sexual desire' oligarch 'government in which a small group exercises control' SEE ALL Time Traveler! Explore the year a word first appeared Definition of non-euclidean : not assuming or in accordance with all the postulates of Euclid's Elements non-euclidean geometry First Known Use of non-euclidean 1872 See Words from the same year NEW! Time Traveler Learn More about non-euclidean See words that rhyme with non-euclidean Seen and Heard What made you want to look up non-euclidean? Please tell us where you read or heard it (including the quote, if possible). show hide