semisimple

Adjective

 * 1)  In which each submodule is a direct summand.
 * 2)  diagonalizable.
 * 3)  For which every invariant subspace has an invariant complement, equivalent to the minimal polynomial being squarefree.
 * 4)  Being a direct sum of simple Lie algebras.
 * 5)  Being a linear algebraic group whose radical of the identity component is trivial.

Etymology
From.