- any echinoderm of the class Echinoidea, having a somewhat globular or discoid form, and a shell composed of many calcareous plates covered with projecting spines.
- a 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.
Origin of sea urchin
First recorded in 1585–95
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
Examples from the Web for sea urchin
A name in our northern isles for the sea-urchin, Echinus marinus.The Sailor's Word-Book
William Henry Smyth
On my way to the front of the peninsula, I looked for “sea-urchin,” but none fell in my way.The Boy Tar
You know, from the second lecture, what a gastrula of our sea-urchin is.The Science and Philosophy of the Organism
The sea-urchin can thus advance with ease, and even rapidity.
The body of the sea-urchin is furnished with a species of spine.
- 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