单词：pu 

名词

• 
  [1.n.pu] (同义词:[plutonium( n. [化] 钚 )]  [Pu(=paid up 付清 )]  [atomic_number_94]  )
• 
  注释列句：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
• 上位词 -> [chemical_element]  [substance( n. 物质, 实质, 主旨 )]  [matter( n. 事件, 问题, 物质, 内容, 实质, 原因, (印刷或书写的)文件, (文章或讲话等的)素材 vi. 有关系, 要紧 )]  [physical_entity]  [entity( n. 实体 )] 
• 下位词 -> [plutonium_239]