1. Cereal plants, such as corn, wheat, or rye, or a seed of one of them. 2. A minute, hard particle of any substance, as of sand. 3. (gr) A unit of weight, 160 dram (apoth. or troy), 1437.5 avoirdupois ounce, 1480 troy ounce, 15760 troy pound, 17000 avoirdupois pound; the equivalent of 0.064799 g.. 4. A macroscopically visible cluster of organisms living in tissue of patients with actinomycosis or mycetoma. [L. granum]
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grain 'grān n
1 a) a seed or fruit of a cereal grass
b) the seeds or fruits of various food plants including the cereal grasses and in commercial and statutory usage other plants (as the soybean)
c) plants producing grain
2) a small hard particle or crystal (as of sand or salt)
3) a unit of avoirdupois, Troy, and apothecaries' weight equal to 0.0648 gram or 0.002286 avoirdupois ounce or 0.002083 Troy ounce abbr. gr
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n.
a unit of mass equal to 1/7000 of a pound (avoirdupois). 1 grain = 0.0648 gram.
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(grān) [L. granum] 1. a seed, especially of a cereal plant. 2. the smallest unit of weight in the apothecaries' and avoirdupois systems, equivalent to 64.8 mg; in the apothecaries' system there are 20 grains to the scruple, with 480 grains in 1 ounce; in the avoirdupos system, there are 27.34 grains to the dram, with 437.5 grains in 1 ounce. Abbreviated gr. 3. an individual crystal of a metal or other crystalline structure.Medical dictionary. 2011.