Abmho is a unit of electrical conductance in the emu-cgs system of units

Centimetre gram second system of units

The centimetre–gram–second system is a metric system of physical units based on centimetre as the unit of length, gram as a unit of mass, and second as a unit of time...

 (stands for "electromagnetic units – centimetre gram second"). It's equal to gigasiemens

Siemens (unit)

The siemens is the SI derived unit of electric conductance and electric admittance. Conductance and admittance are the reciprocals of resistance and impedance respectively, hence one siemens is equal to the reciprocal of one ohm, and is sometimes referred to as the mho. In English, the term...

 (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

Centimetre gram second system of units

The centimetre–gram–second system is a metric system of physical units based on centimetre as the unit of length, gram as a unit of mass, and second as a unit of time...

; others include esu-cgs, Gaussian units

Gaussian units

Gaussian units comprise a metric system of physical units. This system is the most common of the several electromagnetic unit systems based on cgs units. It is also called the Gaussian unit system, Gaussian-cgs units, or often just cgs units...

, and Lorentz–Heaviside units. In these other systems, the abmho is not one of the units.