Nonabelian group
In mathematics, and specifically in group theory, a nonabelian group, sometimes called a noncommutative group, is a group ( G, ∗ ) in which there exists at least one pair of elements a and b of G, such that a ∗ b ≠ b ∗ a.[1][2] This class of groups contrasts with the abelian groups. (In an abelian group, all pairs of group elements commute).
Algebraic structure → Group theory Group theory 



Infinite dimensional Lie group

Nonabelian groups are pervasive in mathematics and physics. One of the simplest examples of a nonabelian group is the dihedral group of order 6. It is the smallest finite nonabelian group. A common example from physics is the rotation group SO(3) in three dimensions (rotating something 90 degrees along one axis and then 90 degrees along a different axis is not the same as doing them the other way round).
Both discrete groups and continuous groups may be nonabelian. Most of the interesting Lie groups are nonabelian, and these play an important role in gauge theory.
References
 Dummit, David S.; Foote, Richard M. (2004). Abstract Algebra (3rd ed.). John Wiley & Sons. ISBN 0471433349.
 Lang, Serge (2002). Algebra. Graduate Texts in Mathematics. Springer. ISBN 038795385X.