The Collaborative International Dictionary of English v.0.48:

Pimple \Pim"ple\, n. [AS. p[imac]pelian to blister; cf. L.
   papula pimple.]
   1. (Med.) Any small acuminated elevation of the cuticle,
      whether going on to suppuration or not. "All eyes can see
      a pimple on her nose." --Pope.
      [1913 Webster]

   2. Fig.: A swelling or protuberance like a pimple. "A pimple
      that portends a future sprout." --Cowper.
      [1913 Webster]

WordNet (r) 3.0 (2006):

pimple
    n 1: a small inflamed elevation of the skin; a pustule or
         papule; common symptom in acne [syn: pimple, hickey,
         zit]