The Collaborative International Dictionary of English v.0.48:

Rile \Rile\ (r[imac]l), v. t. [imp. & p. p. Riled (r[imac]ld);
   p. pr. & vb. n. Riling.] [See Roil.]
   1. To render turbid or muddy; to stir up; to roil.
      [1913 Webster]

   2. To stir up in feelings; to make angry; to vex.
      [1913 Webster]

   Note: In both senses provincial in England and colloquial in
         the United States.
         [1913 Webster]

WordNet (r) 3.0 (2006):

rile
    v 1: cause annoyance in; disturb, especially by minor
         irritations; "Mosquitoes buzzing in my ear really bothers
         me"; "It irritates me that she never closes the door after
         she leaves" [syn: annoy, rag, get to, bother, get
         at, irritate, rile, nark, nettle, gravel, vex,
         chafe, devil]
    2: make turbid by stirring up the sediments of [syn: roil,
       rile]