actinide(redirected from actinoid)
Also found in: Dictionary, Thesaurus, Wikipedia.
ActinideAny of the 15 metallic elements with an atomic number between 89 and 103, which fill the 5f electron shell.
Actinides 89Ac, 90Th, 91Pa, 92U, 93Np, 94Pu, 95Am, 96Cm, 97Bk, 98Cf, 99Es, 100Fm, 101Md, 102No, 103Lr
actinide(ak′tĭ-nīd″) [ actin- + -ide]
Any of the radioactive heavy metals designated on the periodic table of elements with atomic numbers 89–103. The actinides include naturally occurring elements, e.g., actinium and uranium, and artificial elements, e.g., fermium.