The Collaborative International Dictionary of English v.0.48:

Ligustrin \Li*gus"trin\ (l[-i]*g[u^]s"tr[i^]n), n. (Chem.)
   A bitter principle found in the bark of the privet
   (Ligustrum vulgare), and extracted as a white crystalline
   substance with a warm, bitter taste; -- called also
   ligustron.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Privet \Priv"et\, n. [Cf. Scot. privie, Prov. E. prim-print,
   primwort. Prob. for primet, and perh. named from being cut
   and trimmed. See, Prim, a., and cf. Prime to prune,
   Prim, n., Prie, n.] (Bot.)
   An ornamental European shrub (Ligustrum vulgare), much used
   in hedges; -- called also prim.
   [1913 Webster]

   Egyptian privet. See Lawsonia.

   Evergreen privet, a plant of the genus Rhamnus. See
      Alatern.

   Mock privet, any one of several evergreen shrubs of the
      genus Phillyrea. They are from the Mediterranean region,
      and have been much cultivated for hedges and for
      fancifully clipped shrubberies.
      [1913 Webster]

WordNet (r) 3.0 (2006):

Ligustrum vulgare
    n 1: deciduous semi-evergreen shrub used for hedges [syn:
         common privet, Ligustrum vulgare]