A`pa·re'jo noun [ Spanish ] A kind of pack saddle used in the American military service and among the Spanish Americans. It is made of leather stuffed with hay, moss, or the like. Found on http://www.encyclo.co.uk/webster/A/100
A large, padded packsaddle designed to handle awkward, heavy loads. Very likely the first type of packsaddle, Unlike the sawbuck, panniers cannot be handled with this saddle.
Found on http://www.xmission.com/~drudy/amm/gloss.html