The Collaborative International Dictionary of English v.0.48:

Subdivide \Sub`di*vide"\, v. t. [imp. & p. p. Subdivided; p.
   pr. & vb. n. Subdividing.] [L. subdividere, sub under +
   dividere to divide. See Divide.]
   To divide the parts of (anything) into more parts; to part
   into smaller divisions; to divide again, as what has already
   been divided.
   [1913 Webster]

         The progenies of Cham and Japhet swarmed into colonies,
         and those colonies were subdivided into many others.
                                                  --Dryden.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Subdivide \Sub`di*vide"\, v. i.
   To be, or to become, subdivided.
   [1913 Webster]

WordNet (r) 3.0 (2006):

subdivide
    v 1: form into subdivisions; "The cells subdivided"
    2: divide into smaller and smaller pieces; "This apartment
       cannot be subdivided any further!"