单词：ill-defined 

形容词

• 
  [1.a.ill-defined] (同义词:[ill-defined(adj.不清楚的, 欠明了的 )]  [unclear( adj. 不清楚的 )]  )
• 
  注释列句：poorly stated or described; "he confuses the reader with ill-defined terms and concepts"
• 反义词 -> [well-defined( adj. 定义明确的, 明确的 )]