The Collaborative International Dictionary of English v.0.48:

Kingship \King"ship\, n.
   The state, office, or dignity of a king; royalty. --Landor.
   king-size

WordNet (r) 3.0 (2006):

kingship
    n 1: the dignity or rank or position of a king

Moby Thesaurus II by Grady Ward, 1.0:

77 Moby Thesaurus words for "kingship":
   acme, authority, authorization, baronetcy, barony,
   be-all and end-all, blue ribbon, caliphate, championship, command,
   control, czardom, directorship, dominion, dukedom, earldom,
   effectiveness, emperorship, empery, empire, first place,
   first prize, headship, hegemony, height, highest, imperialism,
   imperium, influence, jurisdiction, kaiserdom, kaisership, kinghood,
   knight-errantship, knighthood, ladyship, leadership, lordship,
   majesty, management, marquisate, mastership, mastery, maximum,
   most, ne plus ultra, new high, palms, paramountcy, pashadom, power,
   presidency, primacy, princedom, princeship, queenhood, queenship,
   rajaship, record, regnancy, royalty, rule, say, seignioralty,
   seigniory, sovereignty, sultanate, sultanship, supremacy, sway,
   the crown, the throne, top spot, viscountcy, viscountship,
   viscounty, zenith