'astatine' definitions:

Definition of 'astatine'

From: WordNet
noun
A highly unstable radioactive element (the heaviest of the halogen series); a decay product of uranium and thorium [syn: astatine, At, atomic number 85]

Definition of 'astatine'

From: Elements
  • Symbol: At
  • Atomic number: 85
  • Atomic weight: (210)
  • Radioactive halogen element. Occurs naturally from uranium and thorium decay. At least 20 known isotopes. At-210, the most stable, has a half-life of 8.3 hours. Synthesized by nuclear bombardment in 1940 by D.R. Corson, K.R. MacKenzie and E. Segre at the University of California.