Source : Webster's Revised Unabridged Dictionary (1913)

Ohm \Ohm\, n. [So called from the German electrician, G.S. Ohm.]
   (Elec.)
   The standard unit in the measure of electrical resistance,
   being the resistance of a circuit in which a potential
   difference of one volt produces a current of one amp['e]re.
   As defined by the International Electrical Congress in 1893,
   and by United States Statute, it is a resistance
   substantially equal to 10^{9} units of resistance of the
   C.G.S. system of electro-magnetic units, and is represented
   by the resistance offered to an unvarying electric current by
   a column of mercury at the temperature of melting ice 14.4521
   grams in mass, of a constant cross-sectional area, and of the
   length of 106.3 centimeters. As thus defined it is called the
   {international ohm}.

   {Ohm's law} (Elec.), the statement of the fact that the
      strength or intensity of an electrical current is directly
      proportional to the electro-motive force, and inversely
      proportional to the resistance of the circuit.

Source : WordNet®

Ohm's law
     n : electric current is directly proportional to voltage and
         inversely proportional to resistance; I = E/R