Sentence:  In short—which is the strongest proof that can be given of the excellence of her heart, and the <WSD>incorruptibility</WSD> of her honour, she, at eighteen, was as spotless a character at Little Hockley, as the most innocent inhabitant of her age and sex could be at Castlewick. 
Meaning of the word marked with <WSD> tags:  The condition of being incorruptible; honesty.