Sentence:  <WSD>"Xiphopagi</WSD>" are those in which the ensiform processes are united by a cartilaginous bridge. The peritoneum passes for some distance into the connecting structure (the well-known Siamese twins were <WSD>xiphopagi</WSD>). 
Meaning of the word marked with <WSD> tags:  Either of a pair of congenitally joined twins ("Siamese twin") united at the xiphoid process.