sponge (n.) Look up sponge at Dictionary.com
Old English sponge, spunge, from Latin spongia "a sponge," also "sea animal from which a sponge comes," from Greek spongia, related to spongos "sponge," borrowed from an unknown source. The Latin word is the source of Old Saxon spunsia, Middle Dutch spongie, Old French esponge, Spanish esponja, Italian spugna. To throw in the sponge "quit, submit" (1860) is from prizefighting, in reference to the sponges used to cleanse the faces of combatants between rounds (cf. later throw in the towel). Sponge-cake is attested from 1808.
sponge (v.) Look up sponge at Dictionary.com
late 14c., "to soak up with a sponge," from sponge (n.). The slang sense of "to live in a parasitic manner" is attested from 1670s; sponger (n.) in this sense is from 1670s. Originally it was the victim who was known as the sponge (c.1600), because he or she was being "squeezed." Related: Sponged; sponging.