Source : Webster's Revised Unabridged Dictionary (1913)

Mho \Mho\, n. [Anagram of ohm.] (Elec.)
   A unit of conductivity, being the reciprocal of the ohm.

Source : WordNet®

mho
     n : a unit of conductance equal to the reciprocal of an ohm
         [syn: {siemens}, {reciprocal ohm}, {S}]