(v): rub with a circular motion
(v): ask for and get free; be a parasite
(v): come into possession of
(v): erase with a sponge; as of words on a blackboard
(v): remove by or as if by rubbing or erasing
(v): soak up with a sponge
(v): to wash or wipe with or as if with a mop
(v): gather sponges, in the ocean
(v): assemble or get together
(n): a porous mass of interlacing fibers that forms the internal skeleton of various marine animals and usable to absorb water or any porous rubber or cellulose product similarly used
(n): a material having capacity or tendency to absorb another substance
(n): someone able to acquire new knowledge and skills rapidly and easily
(n): someone (especially a child) who learns (as from a teacher) or takes up knowledge or beliefs
(n): a follower who hangs around a host (without benefit to the host) in hope of gain or advantage
(n): a person who accepts the leadership of another
(n): primitive multicellular marine animal whose porous body is supported by a fibrous skeletal framework; usually occurs in sessile colonies
(n): any animal lacking a backbone or notochord; the term is not used as a scientific classification
And of course WeirdNet thinks the most common usage is as a verb...
Also a bread mix, particularly one that is left to ferment before being worked to a dough.
1: A sponge is a porous animal found in the bottom of the ocean.
2: A small porous tool used to wash various thigs such as dishes or cars. Can be synthetic or made by the actual animal.