LACS

a resinous substance secreted as a protective covering by the lac insect, used to make varnish, shellac, sealing wax, dyes, etc.

denoting the ability of normal strains of the bacterium e. coli to metabolize lactose, or the genetic factors involved in this ability (which is lost in some mutant strains)

(in the raf) leading aircraftman or leading aircraftwoman.