Source : Webster's Revised Unabridged Dictionary (1913)

, a scale-shaped insect, the female of which fixes herself on
the bark, and exudes from the margin of her body this resinous
substance.

   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.

   {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}.

Source : WordNet®

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