What is "retention cyst"

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.