halogen

Từ điển WordNet v3.1 - WordNet Dictionary

noun

any of five related nonmetallic elements (fluorine or chlorine or bromine or iodine or astatine) that are all monovalent and readily form negative ions (Freq. 2)
• Hypernyms:
group, grouping
• Hyponyms:
astatine, At, atomic number 85, bromine, Br,
atomic number 35, chlorine, Cl, atomic number 17, fluorine, F,
atomic number 9, iodine, iodin, I, atomic number 53