(n) a solid silvery grey radioactive transuranic element whose atoms can be split when bombarded with neutrons; found in minute quantities in uranium ores but is usually synthesized in nuclear reactors; 13 isotopes are known with the most important being plutonium 239, Syn.atomic number 94, Pu
(n) a highly fissionable isotope of plutonium that is used in atomic weapons and as a reactor fuel; produced by irradiating uranium 238 with slow electrons
a. [ Cf. F. plutonique. See Pluto. ] 1. Of or pertaining to Pluto; Plutonian; hence, pertaining to the interior of the earth; subterranean. [ 1913 Webster ]
2. Of, pertaining to, or designating, the system of the Plutonists; igneous; as, the Plutonic theory. [ 1913 Webster ]
Plutonic action (Geol.), the influence of volcanic heat and other subterranean forces under pressure. -- Plutonic rocks (Geol.), granite, porphyry, and some other igneous rocks, supposed to have consolidated from a melted state at a great depth from the surface. Cf. Intrusive rocks, under Intrusive. -- Plutonic theory. (Geol.) See Plutonism. [ 1913 Webster ]
n. [ Cf. F. plutonisme. ] The theory, early advanced in geology, that the successive rocks of the earth's crust were formed by igneous fusion; -- opposed to the Neptunian theory. [ 1913 Webster ]
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เช่น Secretary of State=รัฐมนตรีต่างประเทศของสหรัฐฯ (ในภาพตัวอย่าง),
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