Sentence:  His arm had been giving him some trouble and Rector was not enough of a medical expert to determine whether it had healed improperly or whether Hino was simply rebelling against the tedious work in the print shop , using the <WSD>stiffness</WSD> in his arm as an excuse . 
Meaning of the word marked with <WSD> tags:  the physical property of being inflexible and hard to bend