"red resinous substance," 1550s (perhaps via Middle French lacce), earlier lacca (early 15c., from Medieval Latin form lacca), from Persian lak, from Hindi lakh (Prakrit lakkha), from Sanskrit laksha "red dye," which according to Klein is literally "one hundred thousand," in reference to the insects that gather in great numbers on the trees and make the resin run out. But others say lakh is an alteration of Sanskrit rakh, from an IE root word for "color, dye" [Watkins]. Still another guess is that Sanskrit laksha is related to English lax, lox "salmon," and the substance was perhaps originally so called from being somewhat the color of salmon [Barnhart].
lac (lāk)
n.
Milk.
A whitish, milky looking liquid.
sticky, resinous secretion of the tiny lac insect, Laccifer lacca, which is a species of scale insect. This insect deposits lac on the twigs and young branches of several varieties of soapberry and acacia trees and particularly on the sacred fig, Ficus religiosa, in India, Thailand, Myanmar (Burma), and elsewhere in Southeast Asia. The lac is harvested predominantly for the production of shellac (q.v.) and lac dye, a red dye widely used in India and other Asian countries. Forms of lac, including shellac, are the only commercial resins of animal origin