The Collaborative International Dictionary of English v.0.48:
Unaccessible \Un`ac*cess"i*ble\, a. Inaccessible. --Herbert. -- Un`ac*cess"i*bleness , n. -- { Un`ac*cess"i*bly, adv. [1913 Webster]WordNet (r) 3.0 (2006):
unaccessible adj 1: capable of being reached only with great difficulty or not at all [syn: inaccessible, unaccessible] [ant: accessible]