Source : Webster's Revised Unabridged Dictionary (1913)

Retention \Re*ten"tion\, n. [L. retentio: cf. F. r['e]tention.
   See {Retain}.]
   1. The act of retaining, or the state of being ratined.

   2. The power of retaining; retentiveness.

            No woman's heart So big, to hold so much; they lack
            retention.                            --Shak.

   3. That which contains something, as a tablet; a ???? of
      preserving impressions. [R.] --Shak.

   4. The act of withholding; retraint; reserve. --Shak.

   5. Place of custody or confinement.

   6. (Law) The right of withholding a debt, or of retaining
      property until a debt due to the person claiming the right
      be duly paid; a lien. --Erskine. Craig.

   {Retention cyst} (Med.), a cyst produced by obstruction of a
      duct leading from a secreting organ and the consequent
      retention of the natural secretions.

Source : WordNet®

retention
     n 1: the act of keeping in your possession [syn: {keeping}, {holding}]
     2: the power of retaining and recalling past experience; "he
        had a good memory when he was younger" [syn: {memory}, {retentiveness}]
     3: the power of retaining liquid; "moisture retentivity of
        soil" [syn: {retentiveness}, {retentivity}]