actinoid

from WordNet (r) 3.0 (2006)

actinoid
    adj 1: having a radial form; "starfish are actinoid--that is,
           they are radially symmetrical"
    n 1: any of a series of radioactive elements with atomic numbers
         89 through 103 [syn: {actinoid}, {actinide}, {actinon}]

from The Collaborative International Dictionary of English v.0.48

Actinoid \Ac"tin*oid\, a. [Gr. ?, ?, ray + -oid.]
   Having the form of rays; radiated, as an actinia.
   [1913 Webster]