A mischievous child. / A street urchin, a child who lives, or spends most of their time, in the streets. / A sea urchin.

plural of urchin

Any of many marine echinoderms, of the class Echinoidea, commonly found in shallow water, having a complex chewing structure named Aristotle's lantern.

(Britain, obsolescent) A child who lives, or spends most of his or her time, in the streets; sometimes a petty thief or pickpocket.

(chemistry) A dense cluster of nanotubes having a form resembling a sea urchin, especially one made from vanadium oxides.

plural of sea urchin

plural of heart urchin

Any echinoderm of the class Spatangoida.

A porcupine fish.

plural of urchin fish