Degeneracy refers to orbitals that have exactly the same energy; such orbitals are said to be degenerate. In an isolated atom, for example, the three p orbitals of a given subshell are degenerate. The concept matters for electron filling, since Hund's rule governs how electrons occupy a set of degenerate orbitals.

简并指能量完全相同的轨道;这样的轨道称为简并轨道。例如,在孤立原子中,某一亚层的三个 p 轨道是简并的。这一概念对电子填充很重要,因为洪特规则规定了电子如何占据一组简并轨道。