The Collaborative International Dictionary of English v.0.48:

Myrtle \Myr"tle\ (m[~e]r"t'l), n. [F. myrtil bilberry, prop., a
   little myrtle, from myrte myrtle, L. myrtus, murtus, Gr.
   my`rtos; cf. Per. m[=u]rd.] (Bot.)
   A species of the genus Myrtus, especially Myrtus
   communis. The common myrtle has a shrubby, upright stem,
   eight or ten feet high. Its branches form a close, full head,
   thickly covered with ovate or lanceolate evergreen leaves. It
   has solitary axillary white or rosy flowers, followed by
   black several-seeded berries. The ancients considered it
   sacred to Venus. The flowers, leaves, and berries are used
   variously in perfumery and as a condiment, and the
   beautifully mottled wood is used in turning.
   [1913 Webster]

   Note: The name is also popularly but wrongly applied in
         America to two creeping plants, the blue-flowered
         periwinkle and the yellow-flowered moneywort. In the
         West Indies several myrtaceous shrubs are called
         myrtle.
         [1913 Webster]

   Bog myrtle, the sweet gale.

   Crape myrtle. See under Crape.

   Myrtle warbler (Zool.), a North American wood warbler
      (Dendroica coronata); -- called also myrtle bird,
      yellow-rumped warbler, and yellow-crowned warbler.

   Myrtle wax. (Bot.) See Bayberry tallow, under Bayberry.


   Sand myrtle, a low, branching evergreen shrub (Leiophyllum
      buxifolium), growing in New Jersey and southward.

   Wax myrtle (Myrica cerifera). See Bayberry.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Crape \Crape\ (kr[=a]p), n. [F. cr[^e]pe, fr. L. crispus curled,
   crisped. See Crisp.]
   A thin, crimped stuff, made of raw silk gummed and twisted on
   the mill. Black crape is much used for mourning garments,
   also for the dress of some clergymen.
   [1913 Webster]

         A saint in crape is twice a saint in lawn. --Pope.
   [1913 Webster]

   Crape myrtle (Bot.), a very ornamental shrub
      (Lagerstroemia Indica) from the East Indies, often
      planted in the Southern United States. Its foliage is like
      that of the myrtle, and the flower has wavy crisped
      petals.

   Oriental crape. See Canton crape.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

crape myrtle \crape myrtle\ n.
   an tall East Indian and Chinese shrub (Lagerstroemia indica
   of the loosestrife family, commonly planted in Southern and
   Western U. S. as an ornamental shrub. It has clusters of red,
   white, purple, or pink flowers.

   Syn: crepe myrtle, crepe flower, Lagerstroemia indica.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

crape myrtle
    n 1: ornamental shrub from eastern India commonly planted in the
         southern United States [syn: crape myrtle, crepe
         myrtle, crepe flower, Lagerstroemia indica]