What is "jigger mast"

Jigger \Jig"ger\, n. [See Jig, n. & v.]

1. One who, or that which, jigs; specifically, a miner who sorts or cleans ore by the process of jigging; also, the sieve used in jigging.

2. (Pottery)

   1. A horizontal table carrying a revolving mold, on which earthen vessels are shaped by rapid motion; a potter's wheel.

   2. A template or tool by which vessels are shaped on a potter's wheel.

3. (Naut.)

   1. A light tackle, consisting of a double and single block and the fall, used for various purposes, as to increase the purchase on a topsail sheet in hauling it home; the watch tackle.
      --Totten.

   2. A small fishing vessel, rigged like a yawl. [New Eng.]

   3. A supplementary sail. See Dandy, n., 2 (b) .

4. A pendulum rolling machine for slicking or graining leather; same as Jack, 4 (i) .

5. A small glass or measuring vessel holding 11/2 ounces (45 ml), used mostly for measuring liquor or drinking whiskey; also, the quantity of liquid held in a jigger.

6. A thingamajig. [Colloq.] Jigger mast. (Naut.)

   1. The after mast of a four-masted vessel.

   2. The small mast set at the stern of a yawl-rigged boat.

n. (alternative spelling of jiggermast English)