Abmho is a unit of electrical conductance in the emu-cgs system of units (stands for "electromagnetic units – centimetre gram second"). It's equal to gigasiemens (inverse of nano-ohm). Also known as absiemens.
The emu-cgs units are one of several systems of electromagnetic units within the centimetre gram second system of units; others include esu-cgs, Gaussian units, and Lorentz–Heaviside units. In these other systems, the abmho is not one of the units.