You don't specify which face you want to know the name of, both sides are "faces", presumably you do mean the "head" side, which is indeed called the obverse.
We believe the answer about obverse and reverse changing their meanings is incorrect, but there are many coin issues where the obverse does not have a head on it, perhaps a coat-of-arms instead, and sometimes a reverse does have a head instead or in addition to that on the obverse.
There is a definition and brief explanation of obverse, reverse and other numismatic terms at:-
http://www.24carat.co.uk/numismaticterms.html