At

Từ điển WordNet v3.1 - WordNet Dictionary

noun

a highly unstable radioactive element (the heaviest of the halogen series);
a decay product of uranium and thorium
• Syn:
astatine, atomic number 85
• Hypernyms:
chemical element, element, halogen

• Từ đồng nghĩa / Synonyms:
  astatine, At, atomic number 85