The Collaborative International Dictionary of English v.0.48:

Anil \An"il\, n. [F. anil, Sp. an[imac]l, or Pg. anil; all fr.
   Ar. an-n[imac]l, for al-n[imac]l the indigo plant, fr. Skr.
   n[imac]la dark blue, n[imac]l[imac] indigo, indigo plant. Cf.
   Lilac.] (Bot.)
   A West Indian plant (Indigofera anil), one of the original
   sources of indigo; also, the indigo dye.
   [1913 Webster]

WordNet (r) 3.0 (2006):

anil
    n 1: a blue dye obtained from plants or made synthetically [syn:
         anil, indigo, indigotin]
    2: shrub of West Indies and South America that is a source of
       indigo dye [syn: anil, Indigofera suffruticosa,
       Indigofera anil]