The Collaborative International Dictionary of English v.0.48:

Nominally \Nom"i*nal*ly\, adv.
   In a nominal manner; by name; in name only; not in reality.
   --Burke.
   [1913 Webster]

WordNet (r) 3.0 (2006):

nominally
    adv 1: in name only; "nominally he is the boss"

Moby Thesaurus II by Grady Ward, 1.0:

42 Moby Thesaurus words for "nominally":
   apparently, artificially, at a bargain, at a sacrifice,
   at budget prices, at cost, at cost price, at piggy-bank prices,
   at prime cost, at reduced rates, at small cost, at wholesale,
   cheap, cheaply, erroneously, factitiously, falsely, for a song,
   for pennies, in name only, inexpensively, moderately, namely,
   on the cheap, ostensibly, plausibly, reasonably, sc, scil,
   scilicet, seemingly, spuriously, synthetically, to wit,
   truthlessly, ungenuinely, unnaturally, untruly, unveraciously,
   videlicet, viz, wholesale