The Collaborative International Dictionary of English v.0.48:

Concentrate \Con*cen"trate\ (? or ?), v. t. [imp. & p. p.
   Concentrated; p. pr. & vb. n. Concentrating.] [Pref. con-
   + L. centrum center. Cf. Concenter.]
   1. To bring to, or direct toward, a common center; to unite
      more closely; to gather into one body, mass, or force; to
      fix; as, to concentrate rays of light into a focus; to
      concentrate the attention.
      [1913 Webster]

            (He) concentrated whole force at his own camp.
                                                  --Motley.
      [1913 Webster]

   2. To increase the strength and diminish the bulk of, as of a
      liquid or an ore; to intensify, by getting rid of useless
      material; to condense; as, to concentrate acid by
      evaporation; to concentrate by washing; -- opposed to
      dilute.
      [1913 Webster]

            Spirit of vinegar concentrated and reduced to its
            greatest strength.                    --Arbuthnot.

   Syn: To combine; to condense; to consolidate.
        [1913 Webster]