1. 无懈可击的；无可指摘的
If you describe someone or something as unexceptionable, you mean that they are unlikely to be criticized or objected to, but are not new or exciting, and may have some hidden bad qualities.

1. completely acceptable
not open to exception or reproach

e.g. two unexceptionable witnesses
a judge's ethics should be unexceptionable

Synonym: unimpeachable