Dictionary.net

Lac is a substance formed by an insect, and deposited on different species of trees, chiefly in the East Indies, for example, on Croton lacciferum, and two species of Ficus,-Ficus religiosa, and F. Indica. The various kinds, distinguished in commerce, are stick-lac, which is the substance in its natural state, investing the small twigs of the tree: and seed-lac, which is the same broken off. When melted, it is called shell-lac. Lac was, at one time, used in the form of tincture, as a tonic and astringent; and it still forms part of particular dentifrices.