The Collaborative International Dictionary of English v.0.48:

Chaparajos \Cha`pa*ra"jos\, n. pl. [Mex. Sp.]
   Overalls of sheepskin or leather, usually open at the back,
   worn, esp. by cowboys, to protect the legs from thorny
   bushes, as in the chaparral; -- called also chapareras or
   colloq. chaps. [Sp. Amer.]
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Chapareras \Cha`pa*re"ras\, n. pl. [Mex. Sp.]
   Same as Chaparajos. [Sp. Amer.]
   [Webster 1913 Suppl.]