The Collaborative International Dictionary of English v.0.48:

Multifold \Mul"ti*fold\ (m[u^]l"t[i^]*f[=o]ld), a. [Multi- +
   fold.]
   Many times doubled; manifold; numerous.
   [1913 Webster]

Moby Thesaurus II by Grady Ward, 1.0:

38 Moby Thesaurus words for "multifold":
   allotropic, billion, considerable, diverse, diversiform,
   ever so many, full many, heaped-up, heteromorphic, heteromorphous,
   increased, jillion, manifold, many, metamorphic, metamorphotic,
   million, multifarious, multiform, multiphase, multiple, multiplex,
   multiplied, multitudinal, multitudinous, myriad, no few, not a few,
   numerous, polymorphic, polymorphous, polynomial, protean,
   proteiform, quite some, thousand, very many, zillion