n.[C]

1. 問題，疑難問題
   Measures have been taken to solve traffic problems in big cities.

   業已採取措施以解決大城市的交通問題。

2. 【數】習題，幾何作圖題
3. 難弄的人，引起麻煩的人[S1]
   My kid brother is a real problem.

   我弟弟真是個難弄的人。

n.

1. an unwelcome or harmful matter needing to be dealt with and overcome.
   ▸a thing that is difficult to achieve.
2. Physics  & Mathematics  an inquiry starting from given conditions to investigate or demonstrate something.
3. (in chess) an arrangement of pieces in which the solver has to achieve a specified result.