a.

1. 顽皮的，淘气的；撒野的
   You ought to be stricter with him. He's very naughty.

   你该对他更严格一些。他很调皮。

2. 【婉】猥亵的，淫乱的
   Nice boys do not use naughty words.

   好孩子不说下流话。

adj.

1. (especially of a child) disobedient; badly behaved.
2. informal mildly rude or indecent.
3. archaic wicked.