SO(10) (physics)
In particle physics, one of the grand unified theories (GUT) is based on the SO(10) Lie group. (The Lie group involved is not really the special orthogonal group SO(10), but rather its double cover Spin(10); but calling it SO(10) is the standard convention.)
Before SU(5), Harald Fritzsch and Peter Minkowski and independently Howard Georgi found that all the matter contents are incorporated into a single representation, spinorial 16 of SO(10). (Historical note: the before in the previous sentence is misleading: Georgi found the SO(10) theory a few hours before finding SU(5) at the end of 1973.)
Read more about SO(10) (physics): Important Subgroups, Spontaneous Symmetry Breaking, The Electroweak Higgs and The Doublet-triplet Splitting Problem, Matter, Proton Decay