The Collaborative International Dictionary of English v.0.48:

Peaky \Peak"y\ (p[=e]k"[y^]), a.
   1. Having a peak or peaks. --Tennyson.
      [1913 Webster]

   2. Sickly; peaked. [Colloq.]
      [1913 Webster]

WordNet (r) 3.0 (2006):

peaky
    adj 1: having or as if having especially high-pitched spots;
           "absence of peaky highs and beefed-up bass" [syn:
           peaky, spiky]

Moby Thesaurus II by Grady Ward, 1.0:

34 Moby Thesaurus words for "peaky":
   acicular, acuminate, acute, ailing, ashen, cuspidate, drained,
   drawn, emaciated, feeble, gaunt, haggard, hollow-eyed, ill, infirm,
   pale, pallid, pasty, peaked, peaking, pinched, sallow, sharp, sick,
   sickly, unhealthy, unwell, unwholesome, wan, washed out, wasted,
   waxen, weak, whey-faced