Sentence:  Observant visitors to any prison will quickly recognize <WSD>commonalties</WSD> in its inmate population. Not only do shared traits exist among the inmate population of any particular institution (intra-prison <WSD>commonalties</WSD>) but <WSD>commonalties</WSD> also exist among inmates nationwide (inter-prison <WSD>commonalties</WSD>). 
Meaning of the word marked with <WSD> tags:  A shared feature.