The Collaborative International Dictionary of English v.0.48:

Luxuriant \Lux*u"ri*ant\, a. [L. luxurians, p. pr. of luxuriare:
   cf. F. luxuriant. See Luxuriate.]
   1. Exuberant in growth; rank; excessive; profuse; very
      abundant; as, a luxuriant growth of grass; luxuriant
      foliage.
      [1913 Webster]

            Prune the luxuriant, the uncouth refine. --Pope.
      [1913 Webster]

   2. Producing luxuriant growth; very fertile; -- of soil.
      [PJC]

   3. Having or producing an abundance of elaborate details;
      unrestrained; -- of imagery or ornamentation.
      [PJC]

   Luxuriant flower (Bot.), one in which the floral envelopes
      are overdeveloped at the expense of the essential organs.
      [1913 Webster]