whose integrity can't be doubted. Unable to recall the adjective for that

What adj can you use to describe a person whose integrity can't be questioned. Someone who has proved himself many times that can't be doubted.. Or who is impeccable at doing particular stuff that you can trust him blindly.

for instance, what could I use in the following blank?

Everyone had to give an interview to be selected for the next round, while Raj, who had been proven a/an _______ engineer, got bypassed into the finals.

Solution 1:

An adjective for someone 'whose integrity cannot be doubted' is unimpeachable. Here are a couple of dictionary examples:

Merriam-Webster:

• reliable beyond a doubt

e.g. a person of unimpeachable integrity

https://www.merriam-webster.com/dictionary/unimpeachable

Collins English:

• 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.

https://www.collinsdictionary.com/dictionary/english/unimpeachable