adj.
无能的；笨的

[ adj ]
totally uninformed about what is going on; not having even a clue from which to infer what is occurring
<adj.all>

clueless \clueless\ adj.
1. not providing any clue.
[PJC]

2. completely uninformed or unaware; hopelessly ignorant;
utterly bewildered.
[PJC]