The Collaborative International Dictionary of English v.0.48:

Spiky \Spik"y\ (sp[imac]k"[y^]), a.
   1. Like a spike; spikelike.
      [1913 Webster]

            These spiky, vivid outbursts of metallic vapors.
                                                  --C. A. Young.
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   2. Having a sharp point, or sharp points; furnished or armed
      with spikes.
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            Or by the spiky harrow cleared away.  --Dyer.
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            The spiky wheels through heaps of carnage tore.
                                                  --Pope.
      [1913 Webster]

WordNet (r) 3.0 (2006):

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