The Collaborative International Dictionary of English v.0.48:

Radiolaria \Ra`di*o*la"ri*a\
   (r[=a]`d[i^]*[-o]*l[=a]"r[i^]*[.a]), n. pl. [NL. See
   Radioli.] (Zool.)
   Order of rhizopods, usually having a siliceous skeleton, or
   shell, and sometimes radiating spicules. The pseudopodia
   project from the body like rays. It includes the
   polycystines. See Polycystina.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Radiolaria
    n 1: marine protozoa [syn: Radiolaria, order Radiolaria]