1. 1. Any of numerous aquatic, chiefly marine invertebrate animals of the phylum Porifera, characteristically having a porous skeleton composed of fibrous material or siliceous or calcareous spicules and often forming irregularly shaped colonies attached to an underwater surface.
   2. The light, fibrous, flexible, absorbent skeleton of certain of these organisms, used for bathing, cleaning, and other purposes.
2. 1. Porous plastics, rubber, cellulose, or other material, similar in absorbency to this skeleton and used for the same purposes.
   2. Metal in a porous, brittle form, as after the removal of other metals in processing, used as a raw material in manufacturing.
3. A gauze pad used to absorb blood and other fluids, as in surgery or the dressing of a wound.
4. A small absorbent contraceptive pad that contains a spermicide and is placed against the cervix of the uterus before sexual intercourse.
5. Dough that has been or is being leavened.
6. A light cake, such as sponge cake.
7. A sponge bath.
8. One who habitually depends on others for one's own maintenance.
9. 1. Informal. A glutton.
   2. Slang. A drunkard.

1. To moisten, wipe, or clean with or as if with a sponge: sponge off the table.
2. To wipe out; erase.
3. To absorb with or as if with a sponge: sponge up the mess.
4. Informal. To obtain free: sponge a meal.

1. To fish for sponges.
2. Informal. To live by relying on the generosity of others: sponged off her parents.

[Middle English, from Old English, from Latin spongia, from Greek spongiā, from spongos.]

The American Heritage® Dictionary of the English Language, Fourth Edition Copyright © 2007, 2000 by Houghton Mifflin Company. Updated in 2009. Published by Houghton Mifflin Company. All rights reserved.