Anapole

In physics, an anapole is a system of currents that does not radiate into the far field. The term "anapole" first appeared in the work of Zel'dovich, in which he thanks A. S. Kompaneets, who first proposed the name.

An anapole is a system of currents that transforms under all transformations of the symmetry group O(3) as a certain multipole (or the corresponding vector spherical harmonic), but does not radiate to the far field.

Photonics
In photonics, anapoles first appeared in 2015 as zeros in the Mie-coefficient of a particular multipole in the scattering spectrum. They can also be explained as destructive interference of a "cartesian multipole" and a "toroidal multipole". The anapole state is not an eigenmode. Total scattering cross-section is not zero in the anapole state, due to the contribution of other multipoles.

The terms "anapole" and toroidal moment were once used synonymously, but this ended.