au fait
adjective /ˌəʊ ˈfeɪ/
/ˌəʊ ˈfeɪ/
[not before noun] (from French)- au fait (with something) completely familiar with something
- I'm new here so I'm not completely au fait with the system.
Word Originmid 18th cent.: from French, literally ‘to the fact, to the point’.