lac noun1.
[lak] Also
lack, (earlier)
lacca. See also
LAKE noun3.
LME.[(medieval Latin lac, lac(c)a from) Portuguese lac(c)a from Hindi lākh, Persian lāk. Cf. SHELLAC.]1. The dark-red resinous incrustation secreted as a protective covering by the females of certain homopteran insects (esp.
Laccifer lacca) parasitic on SE Asian trees, used (esp. in the Indian subcontinent) to make shellac and dye.
LME.seed-lac: ground in water to remove the dye.
stick-lac untreated lac encrusted on twigs.
2. The varnish made from lac. Also, any of various resinous wood varnishes. Cf.
LACQUER noun 2, 3.
L16-E18.3. Ware coated with lac or lacquer.
M17.4. The colour of lac; crimson. Also, a pigment prepared from lac. Cf.
LAKE noun3 1.
L17-M18.
Comb.:
lac-dye a brilliant scarlet dye prepared from lac;
lac-insect any lac-producing insect, esp.
Laccifer lacca.
[TahlilGaran] English Dictionary ▲
lac noun2.
[lak] M20.[Abbreviation of LACTOSE.]Biology. Used (usu.
attrib. and printed in italics) orig. to denote the ability (of normal individuals) or inability (of mutants) of the bacterium
Escherichia coli to metabolize lactose, and now also to designate (the parts of) the genetic system involved in this ability. Also, a
lac+ bacterium; the
lac operon.
Comb.:
lac operon a group of adjacent genes in
E. coli which, in the presence of lactose, cause the synthesis of the enzymes required for lactose metabolism.
[TahlilGaran] English Dictionary ▲