1. 无过失的：unimaginative 缺乏想象力的 | unimpeachable 无过失的 | unimpeachably 无可指责地

2. 无可指摘的,无可置疑的：indefatigable不知疲倦的 | unimpeachable无可指摘的,无可置疑的 | irreproachable不可指责的,无过失的

3. 无懈可击的/无可指责的/无过失的：unimpaired /健全/ | unimpeachable /无懈可击的/无可指责的/无过失的/ | unimpeachably /无可指责地/

4. 完美无瑕：regression 退步 | unimpeachable 完美无瑕 | parable 寓言

1. 无可怀疑的；完全可靠的
If you describe someone as unimpeachable, you mean that they are completely honest and reliable.

e.g. He said all five were men of unimpeachable character.
他说这五个都是品格完美无缺的人。
e.g. ...an unimpeachable source.
可靠的来源

adj

1. completely acceptable
not open to exception or reproach

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

Synonym: unexceptionable

2. free of guilt
not subject to blame

e.g. has lived a blameless life
of irreproachable character
an unimpeachable reputation

Synonym: blamelessinculpableirreproachable

3. beyond doubt or reproach

e.g. an unimpeachable source