The Potency of a homeopathic remedy refers to the number of successive dilutions that a substance is subjected to before being used as a remedy.  In contrast to conventional pharmacology, in homeopathy potency is directly proportional to the degree of dilution.  Thus when a homeopath speaks of "high potency"  he or she refers to a large number of dilutions.  

Dilutions are performed as ten or one hundred fold steps.  Dilutions of 1:10 are designated in the U.S. by the Roman Numeral X (1X = 1/10, 2X = 1/100, 3X = 1/1000, etc).  Dilutions of 1:100 are designated by the Roman Numeral C (1C = 1/100, 2C=1/10,000, 3C = 1/1,000,000, etc).  Dilutions are always performed serially (i.e., one part of a 1X solution or powder is added to 9 parts of solvent or lactose to make a 2X preparation; then the process is repeated using the @X solution to make a 3X solution and so on) with succussion or trituration following each step.  

 

 

From The Preparation of Medicines, The Organon, 6th Ed

A Homeopath describes potency