actinoid
adjective
ac·ti·noid
| \ ˈak-tə-ˌnȯid
\
\
Definition of actinoid
(Entry 1 of 2)
1
: resembling a ray especially of a radially symmetrical animal
2
: exhibiting radial symmetry
actinoid
noun
ac·ti·noid
| \ ˈak-tə-ˌnȯid
\
\
plural actinoids
Definition of actinoid (Entry 2 of 2)
chemistry
: actinide
The actinoid elements (or actinides; An) constitute a series of 14 elements which are formed by the progressive filling of the 5f electron shell and follow actinium in the periodic table (atomic numbers 90-103).— Mirtat Bouroushian, Electrochemistry of Metal Chalcogenides, 2010
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