The Collaborative International Dictionary of English v.0.48:

Sketch \Sketch\, v. t. [imp. & p. p. Sketched; p. pr. & vb. n.
   Sketching.] [Cf D. schetsen, It. schizzare. See Sketch,
   n.]
   1. To draw the outline or chief features of; to make a rought
      of.
      [1913 Webster]

   2. To plan or describe by giving the principal points or
      ideas of.
      [1913 Webster]

   Syn: To delineate; design; draught; depict.
        [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sketch \Sketch\, n. [D. schets, fr. It. schizzo a sketch, a
   splash (whence also F. esquisse; cf. Esquisse.); cf. It.
   schizzare to splash, to sketch.]
   An outline or general delineation of anything; a first rough
   or incomplete draught or plan of any design; especially, in
   the fine arts, such a representation of an object or scene as
   serves the artist's purpose by recording its chief features;
   also, a preliminary study for an original work.
   [1913 Webster]

   Syn: Outline; delineation; draught; plan; design.

   Usage: Sketch, Outline, Delineation. An outline gives
          only the bounding lines of some scene or picture. A
          sketch fills up the outline in part, giving broad
          touches, by which an imperfect idea may be conveyed. A
          delineation goes further, carrying out the more
          striking features of the picture, and going so much
          into detail as to furnish a clear conception of the
          whole. Figuratively, we may speak of the outlines of a
          plan, of a work, of a project, etc., which serve as a
          basis on which the subordinate parts are formed, or of
          sketches of countries, characters, manners, etc.,
          which give us a general idea of the things described.
          --Crabb.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Sketch \Sketch\, v. i.
   To make sketches, as of landscapes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sketch
    n 1: preliminary drawing for later elaboration; "he made several
         studies before starting to paint" [syn: sketch, study]
    2: a brief literary description [syn: sketch, vignette]
    3: short descriptive summary (of events) [syn: sketch,
       survey, resume]
    4: a humorous or satirical drawing published in a newspaper or
       magazine [syn: cartoon, sketch]
    v 1: make a sketch of; "sketch the building" [syn: sketch,
         chalk out]
    2: describe roughly or briefly or give the main points or
       summary of; "sketch the outline of the book"; "outline his
       ideas" [syn: sketch, outline, adumbrate]