Noun. A plastic bag (usually from a grocery store, bodega or other ghetto-mart) that has been inflated and borne aloft by the wind, giving it a jellyfish like appearance. Common in neighborhoods where littering is acceptable but walking on a sidewalk isn't.
I almost ran over that ho because she stepped out infront of me right as an urban jellyfish splatted up against my windshield.
A used condom discarded within an urban setting such as a busy street or project courtyard.
Ahhh shit, the other day I slipped on an urban jellyfish lying on my stoop and almost wrecked my new dunks. Then later I seen my two pit-bulls playing tug-o-war with the same jellyfish and it snapped, the jiz was all over their face.