The Collaborative International Dictionary of English v.0.48:

Algorism \Al"go*rism\, Algorithm \Al"go*rithm\, n. [OE.
   algorism, algrim, augrim, OF. algorisme, F. algorithme (cf.
   Sp. algoritmo, OSp. alguarismo, LL. algorismus), fr. the Ar.
   al-Khow[=a]rezm[imac] of Khow[=a]rezm, the modern Khiwa,
   surname of Abu Ja'far Mohammed ben Mus[=a], author of a work
   on arithmetic early in the 9th century, which was translated
   into Latin, such books bearing the name algorismus. The
   spelling with th is due to a supposed connection with Gr. ?
   number.]
   1. The art of calculating by nine figures and zero;
      computation with Arabic figures.
      [1913 Webster]

   2. the Arabic system of numeration.

   Syn: decimal system
        [WordNet 1.5]

   3. The art of calculating with any species of notation; as,
      the algorithms of fractions, proportions, surds, etc.
      [1913 Webster]

WordNet (r) 3.0 (2006):

algorism
    n 1: the Arabic (or decimal) system of numeration
    2: computation with Arabic figures