The simplest soliton is the domain wall with co-dimension one, and the next simplest is the vortex with co-dimension two, whereas the co-dimension three (four) soliton is called monopole (instanton).
a two-dimensional singularity hypothesized in string theory
الواصلة
a two-di·men·sion·al sin-gu-la-ri-ty hy-poth-e-sized in string the-o-ry