The Collaborative International Dictionary of English v.0.48:

Group \Group\, v. t. [imp. & p. p. Grouped; p. pr. & vb. n.
   Grouping.] [Cf. F. grouper. See Group, n.]
   To form a group of; to arrange or combine in a group or in
   groups, often with reference to mutual relation and the best
   effect; to form an assemblage of.
   [1913 Webster]

         The difficulty lies in drawing and disposing, or, as
         the painters term it, in grouping such a multitude of
         different objects.                       --Prior.
   [1913 Webster]

   Grouped columns (Arch.), three or more columns placed upon
      the same pedestal.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Grouping \Group"ing\ (gr[=oo]p"[i^]ng), n. (Fine Arts)
   The disposal or relative arrangement of figures or objects,
   as in, drawing, painting, and sculpture, or in ornamental
   design.
   [1913 Webster]

WordNet (r) 3.0 (2006):

grouping
    n 1: any number of entities (members) considered as a unit [syn:
         group, grouping]
    2: the activity of putting things together in groups
    3: a system for classifying things into groups [syn: grouping,
       pigeonholing]