The Collaborative International Dictionary of English v.0.48:

Petal \Pet"al\ (p[e^]t"al; 277), n. [Gr. pe`talon a leaf, a leaf
   or plate of metal, fr. pe`talos outspread, broad, flat: cf.
   F. p['e]tale. See Fathom.]
   1. (Bot.) One of the leaves of the corolla, or the colored
      leaves of a flower. See Corolla, and Illust. of
      Flower.
      [1913 Webster]

   2. (Zool.) One of the expanded ambulacra which form a rosette
      on the black of certain Echini.
      [1913 Webster]

WordNet (r) 3.0 (2006):

petal
    n 1: part of the perianth that is usually brightly colored [syn:
         petal, flower petal]

Moby Thesaurus II by Grady Ward, 1.0:

45 Moby Thesaurus words for "petal":
   androecium, anther, blade, bract, bracteole, bractlet, calyx,
   carpel, corolla, corolla tube, corona, cotyledon, epicalyx, flag,
   floral leaf, foliole, frond, glume, gynoecium, involucre,
   involucrum, lamina, leaf, leaflet, lemma, ligule, megasporophyll,
   microsporophyll, needle, perianth, pile, pine needle, pistil,
   receptacle, seed leaf, sepal, spathe, spear, spire, stamen, stigma,
   stipula, stipule, style, torus



U.S. Gazetteer Places (2000):

Petal, MS -- U.S. city in Mississippi
   Population (2000):    7579
   Housing Units (2000): 3208
   Land area (2000):     9.670087 sq. miles (25.045409 sq. km)
   Water area (2000):    0.015214 sq. miles (0.039404 sq. km)
   Total area (2000):    9.685301 sq. miles (25.084813 sq. km)
   FIPS code:            56800
   Located within:       Mississippi (MS), FIPS 28
   Location:             31.346740 N, 89.255485 W
   ZIP Codes (1990):     39465
   Note: some ZIP codes may be omitted esp. for suburbs.
   Headwords:
    Petal, MS
    Petal