- any echinoderm of the class Echinoidea, such as Echinus esculentus (edible sea urchin), typically having a globular body enclosed in a rigid spiny test and occurring in shallow marine waters
WordReference Random House Learner's Dictionary of American English © 2026
ˈsea ˌur•chin, n. [countable]
WordReference Random House Unabridged Dictionary of American English © 2026- Invertebratesa small, round sea animal with a shell of plates covered with spines.
sea′ ur′chin,
- Invertebratesany echinoderm of the class Echinoidea, having a somewhat globular or discoid form, and a shell composed of many calcareous plates covered with projecting spines.
- Plant Biologya tall evergreen shrub or small tree, Hakea laurina, of Australia, having narrow leaves and dense, globe-shaped clusters of crimson flowers with long yellow stamens.
- 1585–95
Collins Concise English Dictionary © HarperCollins Publishers::
sea urchin n
'sea urchin' also found in these entries (note: many are not synonyms or translations):