Sentence:  One of the <WSD>onagers</WSD>, however, having hurt its leg, could not be harnessed at present, and a few days' rest was necessary. 
Meaning of the word marked with <WSD> tags:  The Asiatic wild ass or hemione ("Equus hemionus"), an animal of the horse family native to Asia; specifically, the (Persian onager), (Persian wild ass), or (Persian zebra) ("(Equus hemionus onager)").