The Collaborative International Dictionary of English v.0.48:

Variorum \Va`ri*o"rum\, a. [L., abbrev. fr. cum notis variorum
   with notes of various persons.]
   Containing notes by different persons; -- applied to a
   publication; as, a variorum edition of a book.
   [1913 Webster]

WordNet (r) 3.0 (2006):

variorum
    n 1: an edition containing various versions of a text or notes
         by various scholars or editors [syn: variorum, variorum
         edition]