2 definitions found From WordNet (r) 2.0 [wn]: actinoid adjective: having a radial form; "starfish are actinoid--that is, they are radially symmetrical" noun: any of a series of radioactive elements with atomic numbers 89 through 103 [syn: {actinide}, {actinon}] From The Collaborative International Dictionary of English v.0.44 [gcide]: Actinoid \Ac"tin*oid\, adjective [Gr. ?, ?, ray + -oid.] Having the form of rays; radiated, as an actinia.

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