A Sponge

1. (countable) Any of various marine invertebrates, mostly of the phylum Porifera, that have a porous skeleton often of silica.

Synonyms: sea sponge, bath sponge, poriferan, porifer

2. (countable) A piece of porous material used for washing (originally made from the invertebrates, now often made of plastic).

Synonym: bath sponge

3. (uncountable) A porous material such as sponges consist of.
4. (informal) A heavy drinker.

Synonyms: souse, swill-pot;

5. (countable, uncountable) A type of light cake.

Synonym: sponge cake

6. (countable, uncountable, Britain) A type of steamed pudding.

Synonym: sponge pudding

7. (slang) A person who takes advantage of the generosity of others (abstractly imagined to absorb or soak up the money or efforts of others like a sponge).

Synonyms: freeloader, sponger; scrounger

8. (countable) A form of contraception that is inserted vaginally; a contraceptive sponge.
9. Any sponge-like substance.

• 1 (baking) Dough before it is kneaded and formed into loaves, and after it is converted into a light, spongy mass by the agency of the yeast or leaven.
• 2 Iron from the puddling furnace, in a pasty condition.
• 3 Iron ore, in masses, reduced but not melted or worked.

10. A mop for cleaning the bore of a cannon after a discharge. It consists of a cylinder of wood, covered with sheepskin with the wool on, or cloth with a heavy looped nap, and having a handle, or staff.
11. The extremity, or point, of a horseshoe, corresponding to the heel.
12. (slang) A nuclear power plant worker routinely exposed to radiation.