Sentence:  The glance of fear, rather than surprise, with which she had watched the motion of the tapestry over the concealed door, implied an apprehension of danger which I could not but suppose well grounded; for Diana Vernon was little subject to the nervous emotions of her sex, and totally <WSD>unapt</WSD> to fear without actual and rational cause. 
Meaning of the word marked with <WSD> tags:  Unaccustomed.