1. 
[syn: abreast(p), au courant, au fait, up on(p)]
The Collaborative International Dictionary of English v.0.48:
Au fait \Au` fait"\ ([=o]` f[asl]"). [F. Lit., to the deed, act,
   or point. Fait is fr. L. factum. See Fact.]
   Expert; skillful; well instructed.
   [1913 Webster]
WordNet (r) 3.0 (2006):
au fait
    adj 1: being up to particular standard or level especially in
           being up to date in knowledge; "kept abreast of the
           latest developments"; "constant revision keeps the book
           au courant"; "always au fait on the latest events"; "up
           on the news" [syn: abreast(p), au courant, au fait,
           up on(p)]
Moby Thesaurus II by Grady Ward, 1.0:
26 Moby Thesaurus words for "au fait":
   able, abreast, acquainted, au courant, au fond, basically,
   becoming, befitting, capable, comme il faut, competent, conforming,
   conversant, correct, decent, fundamentally, good, in essence,
   informed, nice, proper, qualified, right, up, versed, wicked