Merriam-Webster Collegiate Dictionary - subtraction

 noun  Etymology: Middle English subtraccion, from Anglo-French sustraction, ~, from Late Latin ~-, subtractio, from Latin subtrahere  Date: 15th century an act, operation, or instance of subtracting: as  a. the withdrawing or withholding of a right to which an individual is entitled  b. the operation of deducting one number from another