Definition from Wiktionary, the free dictionary
- (countable) Any of various marine invertebrates, mostly of the phylum Porifera, that have a porous skeleton often of silica.
- (countable) A piece of porous material used for washing (originally made from the invertebrates, now often made of plastic).
- (uncountable) A porous material such as sponges consist of.
- (informal) A heavy drinker.
- (countable, uncountable) A type of light cake; sponge cake.
- (countable, uncountable, UK) A type of steamed pudding.
- (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).
- (countable) A form of contraception that is inserted vaginally; a contraceptive sponge.
- (marine invertebrate): sea sponge, bath sponge, poriferan
- (piece of porous material used for washing): bath sponge
- (light cake): sponge cake
- (type of steamed pudding): sponge pudding
- (person): freeloader, sponger
Derived terms 
See also 
marine invertebrate with a porous skeleton
piece of porous material used for washing
informal: heavy drinker
sponge cake — see sponge cake
sponge pudding — see sponge pudding
slang: person who takes advantage of the generosity of others
- (slang) To take advantage of the kindness of others.
- He has been sponging off his friends for a month now.
- The fly is an intruder, and a common smell-feast, that sponges upon other people's trenchers.
- To clean, soak up, or dab with a sponge.
- To suck in, or imbibe, like a sponge.
- (intransitive) To be converted, as dough, into a light, spongy mass by the agency of yeast or leaven.
to take advantage of others