The Collaborative International Dictionary of English v.0.48:

Pariah \Pa"ri*ah\, n. [From Tamil paraiyan, pl. paraiyar, one of
   the low caste, fr. parai a large drum, because they beat the
   drums at certain festivals.]
   [1913 Webster]
   1. One of an aboriginal people of Southern India, regarded by
      the four castes of the Hindus as of very low grade. They
      are usually the serfs of the Sudra agriculturalists. See
      Caste. --Balfour (Cyc. of India).
      [1913 Webster]

   2. An outcast; one despised by society.
      [1913 Webster]

   Pariah dog (Zool.), a mongrel race of half-wild dogs which
      act as scavengers in Oriental cities.

   Pariah kite (Zool.), a species of kite (Milvus govinda)
      which acts as a scavenger in India.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pariah dog
    n 1: ownerless half-wild mongrel dog common around Asian
         villages especially India [syn: pariah dog, pye-dog,
         pie-dog]