lac \lac\, n. per. lak; akin to skr. l=aksh=a: cf. f.
   lague, it.  nl. lacca. cf. lake a color, lacquer,
   litmus.
   a resinous substance produced mainly on the banyan tree, but
   to some extent on other trees, by the laccifer lacca
   formerly coccus lacca, a scale-shaped insect, the female
   of which fixes herself on the bark, and exudes from the
   margin of her body this resinous substance.
   1913 webster

   note: stick-lac is the substance in its natural state,
         incrusting small twigs. when broken off, and the
         coloring matter partly removed, the granular residuum
         is called seed-lac. when melted, and reduced to a
         thin crust, it is called shell-lac or shellac. lac
         is an important ingredient in sealing wax, dyes,
         varnishes, and lacquers.
         1913 webster

   ceylon lac, a resinous exudation of the tree croton
      lacciferum, resembling lac.

   lac dye, a scarlet dye obtained from stick-lac.

   lac lake, the coloring matter of lac dye when precipitated
      from its solutions by alum.

   mexican lac, an exudation of the tree croton draco.
      1913 webster
see also:
lake lacquer litmus laccifer lacca coccus lacca stick-lac 
seed-lac shell-lac shellac ceylon lac croton lacciferum 
lac dye lac lake mexican lac croton draco 

lac dye
     n : scarlet dye like cochineal; extracted with alkali from stick
         lac