The Collaborative International Dictionary of English v.0.48:

Flews \Flews\, n. pl.
   The pendulous or overhanging lateral parts of the upper lip
   of dogs, especially prominent in hounds; -- called also
   chaps. See Illust. of Bloodhound.
   [1913 Webster]

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:

Chaps \Chaps\, n. pl.
   The jaws, or the fleshy parts about them. See Chap. "Open
   your chaps again." --Shak.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Chaps \Chaps\, n. pl.
   Short for Chaparajos. [Colloq.]
   [Webster 1913 Suppl.]

Moby Thesaurus II by Grady Ward, 1.0:

21 Moby Thesaurus words for "chaps":
   bazoo, chops, embouchure, gab, gob, jaw, jaws, jowls, kisser, lips,
   mandibles, maw, maxilla, mouth, mug, mush, muzzle, oral cavity,
   premaxilla, trap, yap