Affirm and Avouch

Affirm verb - To state as a fact usually forcefully.

Avouch is a synonym for affirm in declare topic. In some cases you can use "Avouch" instead a verb "Affirm", when it comes to topics like declare the truth of something.

Avouch verb - To declare (something) to be true or genuine.

Affirm is a synonym for avouch in assert topic. You can use "Affirm" instead a verb "Avouch", if it concerns topics such as vouch for.