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radium therapy
radius
radius of action
radius of curvature
radius vector
radix
RADM
radome
radon
radula
radwaste
RAEC
RAF
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raffia
raffia palm
raffinate
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radon
ra·don [ ráy dòn ]


noun 
Definition:
 
radioactive element: a heavy gaseous radioactive element. Source: radioactive decay of radium, in small quantities in rock and soil. Use: radiotherapy.
Symbol  Rn
[Early 20th century. <radium]
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