non-euclidean

adjective

1. differing from the postulates of Euclid or based upon postulates other than those of Euclid.

1874, from non- + Euclidean.

1. Relating to any of several modern geometries that are based on a set of postulates other than the set proposed by Euclid, especially one in which all of the postulates of Euclidean geometry hold except the parallel postulate. Compare Euclidean.