The Collaborative International Dictionary of English v.0.48:

Gubernatorial \Gu"ber*na*to`ri*al\, a. [L. gubernator governor.
   See Gabernate.]
   Pertaining to a governor, or to government.
   [1913 Webster]

WordNet (r) 3.0 (2006):

gubernatorial
    adj 1: relating to a governor; "gubernatorial election"

Moby Thesaurus II by Grady Ward, 1.0:

37 Moby Thesaurus words for "gubernatorial":
   absolute, aristocratic, authoritarian, autocratic, autonomous,
   bureaucratic, civic, civil, constitutional, democratic, despotic,
   dictatorial, fascist, federal, federalist, federalistic,
   governmental, heteronomous, matriarchal, matriarchic, monarchal,
   monarchial, monarchic, monocratic, official, oligarchal,
   oligarchic, parliamentarian, parliamentary, patriarchal,
   patriarchic, pluralistic, political, republican, self-governing,
   theocratic, totalitarian