Main Entry:

ra·di·o·lar·i·an

Pronunciation:

\ˌrā-dē-ō-ˈler-ē-ən\

Function:

noun

Date:

1875

: any of three classes (Acantharia, Polycystina, and Phaeodaria) of usually spherical chiefly planktonic marine protozoans having radiating threadlike pseudopodia and often a siliceous skeleton of spicules

— radiolarian adjective

[radiolarian illustration]