plural noun Echi·no·cys·toi·da \"+sə̇ˈstȯidə\

Definition of Echinocystoida

  1. :  an order of Silurian fossil echinoids having small irregular spheroidal or flattened tests

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Origin and Etymology of echinocystoida

New Latin, irregular from Echinocystites, fossil genus of Echinodermata (from echin- + -cystis + -ites -ite) + -oida

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