The Collaborative International Dictionary of English v.0.48:

Periwinkle \Per"i*win`kle\, n. [OE. pervenke, AS. pervince, fr.
   L. pervinca.] (Bot.)
   A trailing herb of the genus Vinca.
   [1913 Webster]

   Note: The common perwinkle (Vinca minor) has opposite
         evergreen leaves and solitary blue or white flowers in
         their axils. In America it is often miscalled myrtle.
         See under Myrtle.
         [1913 Webster]

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]

WordNet (r) 3.0 (2006):

myrtle
    n 1: widely cultivated as a groundcover for its dark green shiny
         leaves and usually blue-violet flowers [syn: myrtle,
         Vinca minor]
    2: any evergreen shrub or tree of the genus Myrtus

Easton's 1897 Bible Dictionary:

Myrtle
   (Isa. 41:19; Neh. 8:15; Zech. 1:8), Hebrew hadas, known in the
   East by the name _as_, the Myrtus communis of the botanist.
   "Although no myrtles are now found on the mount (of Olives),
   excepting in the gardens, yet they still exist in many of the
   glens about Jerusalem, where we have often seen its dark shining
   leaves and white flowers. There are many near Bethlehem and
   about Hebron, especially near Dewir Dan, the ancient Debir. It
   also sheds its fragrance on the sides of Carmel and of Tabor,
   and fringes the clefts of the Leontes in its course through
   Galilee. We meet with it all through Central Palestine"
   (Tristram).


U.S. Gazetteer Places (2000):

Myrtle, MN -- U.S. city in Minnesota
   Population (2000):    63
   Housing Units (2000): 36
   Land area (2000):     0.103924 sq. miles (0.269163 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.103924 sq. miles (0.269163 sq. km)
   FIPS code:            44890
   Located within:       Minnesota (MN), FIPS 27
   Location:             43.562649 N, 93.162899 W
   ZIP Codes (1990):
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Myrtle, MN
    Myrtle


U.S. Gazetteer Places (2000):

Myrtle, MS -- U.S. town in Mississippi
   Population (2000):    407
   Housing Units (2000): 183
   Land area (2000):     0.568773 sq. miles (1.473116 sq. km)
   Water area (2000):    0.000000 sq. miles (0.000000 sq. km)
   Total area (2000):    0.568773 sq. miles (1.473116 sq. km)
   FIPS code:            50280
   Located within:       Mississippi (MS), FIPS 28
   Location:             34.558152 N, 89.117436 W
   ZIP Codes (1990):     38650
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Myrtle, MS
    Myrtle