The Collaborative International Dictionary of English v.0.48:

Peakish \Peak"ish\, a.
   1. Of or relating to a peak; or to peaks; belonging to a
      mountainous region. "Her peakish spring." --Drayton. "His
      peakish dialect." --Bp. Hall.
      [1913 Webster]

   2. Having peaks; peaked.
      [1913 Webster]

   3. Having features thin or sharp, as from sickness; hence,
      sickly. [Colloq.]
      [1913 Webster]