1. Any aquatic, chiefly marine animal of the phylum Porifera, having a porous structure and usually a horny, siliceous or calcareous internal skeleton or framework, occurring in large, sessile colonies.
2. The light, yielding, porous, fibrous skeleton or framework of certain animals or colonies of this group; especially, of the genera Spongia and Hippospongia, from which the living matter has been removed, characterized by readily absorbing water and becoming soft when wet while retaining toughness.

Used in bathing, in wiping or cleaning surfaces, etc. Any of various other similar substances, often porous rubber or cellulose, used for washing or cleaning.

3. A person or thing that absorbs something freely: "Her mind was described as a sponge gathering scientific data."
4. Someone who persistently borrows from, or lives, at the expense of others; a sponger; a parasite.
5. Sometimes referring to a drunkard who absorbs alcohol like a sponge.
6. In surgery, a sterile surgical dressing of absorbent material, usually cotton gauze, for wiping or absorbing pus, blood, or other fluids during a surgical operation.
7. A disposable piece of polyurethane foam impregnated with a spermicide for insertion into the vagina as a contraceptive.
8. To concede defeat, yield, give up by "throwing in the sponge: "The early election returns were heavily against her, but she wasn't ready to throw in the sponge."

Living on or in sponges.

A flat absorbent material from 1/2 to 1 inch (1.27 to 2.54 cm) thick, 3 to 6 in. (7.62 to 15.24 cm) in diameter, used as packing to prevent closing or obstruction by intrusion of viscera and for preventing tissue injury: During the operation, abdominal sponges were used to soak up excess fluids.

A sterile, absorbable, water-insoluble gelatin base sponge, used to control capillary bleeding in surgical operations.

It is left in situ (situated naturally) and is absorbed by the patient in from four to six weeks.

A sheet of gelatin, prepared to decrease or stop bleeding when applied to a raw surface.

A bath in which the body is sponged or washed one part at a time without being immersed.

A surgical instrument which clasps a gauze sponge.

Used to apply antiseptics to the skin, cleanse a wound, or sponge away blood from a deep surgical wound.