The Collaborative International Dictionary of English v.0.48:

Yokel \Yo"kel\, n. [Perhaps from an AS. word akin to E. gawk.]
   A country bumpkin. [Eng.] --Dickens.
   [1913 Webster]

WordNet (r) 3.0 (2006):

yokel
    n 1: a person who is not very intelligent or interested in
         culture [syn: yokel, rube, hick, yahoo, hayseed,
         bumpkin, chawbacon]