The Collaborative International Dictionary of English v.0.48:

Factoring \Fac"tor*ing\, n. (Math.)
   The act of resolving into factors.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Factor \Fac"tor\, v. t. [imp. & p. p. Factored (-t[e^]rd); p.
   pr. & vb. n. Factoring.] (Mach.)
   To resolve (a quantity) into its factors.
   [1913 Webster]

WordNet (r) 3.0 (2006):

factoring
    n 1: (mathematics) the resolution of an entity into factors such
         that when multiplied together they give the original entity
         [syn: factorization, factorisation, factoring]