Sentence:  <WSD>Caimans</WSD> are reptiles that are closely related to their Central and South American neighbors, the alligators. Adult <WSD>caimans</WSD> are usually four to six feet (1.8 m) in length. 
Meaning of the word marked with <WSD> tags:  Any of the relatively small crocodilians of genus "Caiman", within family Alligatoridae.