noun
1Embryology
A ridge of thickened ectoderm that appears on either side of the ventral surface of a mammalian embryo, extending from the fore to the rear limb buds, on which the mammary glands form; (also) a line representing this in post-embryonic life, the line occupied by the mammary glands.2Farming
The main pipe or tube which carries milk from a milking shed to a holding tank.
Origin
Late 19th century; earliest use found in Journal of the Royal Microscopical Society. From milk + line.
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