Source : Webster's Revised Unabridged Dictionary (1913)

Pinto \Pin"to\, a. [Sp., painted.]
   Lit., painted; hence, piebald; mottled; pied.

Pinto \Pin"to\, n.
   Any pied animal; esp., a pied or ``painted'' horse.

Pintos \Pin"tos\, n. pl.; sing. {Pinto}. [Sp., painted,
   mottled.] (Eyhnol.)
   A mountain tribe of Mexican Indians living near Acapulco.
   They are remarkable for having the dark skin of the face
   irregularly spotted with white. Called also {speckled
   Indians}.

Source : WordNet®

pinto
     n : a spotted or calico horse or pony