The Collaborative International Dictionary of English v.0.48:

Sponsorship \Spon"sor*ship\ (sp[o^]n"s[~e]r*sh[i^]p), n.
   State of being a sponsor.
   [1913 Webster]

WordNet (r) 3.0 (2006):

sponsorship
    n 1: the act of sponsoring (either officially or financially)

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "sponsorship":
   abetment, advocacy, aegis, auspices, backing, capitalization, care,
   championship, charity, countenance, deficit financing,
   encouragement, favor, financial backing, financial support,
   financing, fosterage, funding, goodwill, grubstake, guarantorship,
   guidance, interest, patronage, patronization, provision of capital,
   seconding, sponsion, stake, subsidy, support, sympathy, tutelage