The Collaborative International Dictionary of English v.0.48:

Peorias \Pe*o"ri*as\, n. pl.; sing. Peoria. (Ethnol.)
   An Algonquin tribe of Indians who formerly inhabited a part
   of Illinois.
   [1913 Webster]

WordNet (r) 3.0 (2006):

Peoria
    n 1: a city in central Illinois on the Illinois River