noun
a person who is well informed or knowledgeable about a particular subject
adjective
having a good understanding or knowledge of a particular subject
-
She is au fait with the latest developments in the field of quantum physics.
-
I'm not really au fait with how to use this new software yet.
-
I'm not au fait with all the drama happening in the office.
-
He is au fait with the intricacies of human behavior.