inaccessible
adj
~ (to sb) very difficult or impossible to reach, approach, or be contacted (by sb); not accessible 难达到的; 不可及的; 不易进入的; 不可接触的
an inaccessible mountain retreat 很难抵达的山间僻静处
His busy schedule made him completely inaccessible to his students. 他的时间排得很满, 学生根本无法和他接触.
(fig 比喻) philosophical theories that are inaccessible to (ie cannot be understood by) ordinary people 普通人无法理解的哲学理论.