I know the question is now closed, but look on many Catholic forums and they will tell you Vigil Mass refers to the masses preceding important festivities such as Easter etc. One I read said there are only 6 Vigils a year. Another "Let's take this opportunity to clear something up. The Saturday evening Mass is in NO sense a Vigil Mass. Since Sunday begins liturgically with First Vespers the so-called Saturday Vigil Mass is simply the Sunday Mass celebrated as soon as Sunday liturgically begins. In contrast, a Vigil Mass always precedes First Vespers or (as with the Easter Vigil) replaces it. With a Vigil Mass the Sunday or Solemnity has not yet started and the Propers of the Mass e.g. the Epistle and Gospel, are entirely different from the Mass of the Sunday or Solemnity. Such is not the case with the Saturday Evening Masses. If you have missals, folks, look them up. You will find no reference to a Saturday "Vigil" Mass."
http://forums.catholic.com/showthread.php?t=73337 I think its use for the Saturday mass may have crept in (in the US, I think not in Britain, at least I've never heard it used there) because it's short and easy for notices etc. But not strictly correct.
The translation workplace 
