What is "sea girdle"

Girdle \Gir"dle\, n. [OE. gurdel, girdel, AS. gyrdel, fr. gyrdan; akin to D. gordel, G. g["u]rtel, Icel. gyr?ill. See Gird, v. t., to encircle, and cf. Girth, n.]

1. That which girds, encircles, or incloses; a circumference; a belt; esp., a belt, sash, or article of dress encircling the body usually at the waist; a cestus.

   Within the girdle of these walls.
   --Shak.

   Their breasts girded with golden girdles.
   --Rev. xv. 6.

2. The zodiac; also, the equator. [Poetic]
   --Bacon.

   From the world's girdle to the frozen pole.
   --Cowper.

   That gems the starry girdle of the year.
   --Campbell.

3. (Jewelry) The line ofgreatest circumference of a brilliant-cut diamond, at which it is grasped by the setting. See Illust. of Brilliant.
   --Knight.

4. (Mining) A thin bed or stratum of stone.
   --Raymond.

5. (Zo["o]l.) The clitellus of an earthworm.

   Girdle bone (Anat.), the sphenethmoid. See under Sphenethmoid.

   Girdle wheel, a spinning wheel.

   Sea girdle (Zo["o]l.), a ctenophore. See Venus's girdle, under Venus.

   Shoulder, Pectoral, & Pelvic, girdle. (Anat.) See under Pectoral, and Pelvic.

   To have under the girdle, to have bound to one, that is, in subjection.