One millionth (1/1,000,000) gram.

synonym: mcg.

Roget 319: gravity, gravitation; weight; heaviness etc. adj.; specific gravity; pondorosity^†, pressure, load; burden, burthen^†; ballast, counterpoise; lump of, mass of, weight of.    lead, millstone, mountain, Ossa on Pelion.    weighing, ponderation^†, trutination^†; weights; avoirdupois weight, troy weight, apothecaries' weight; grain, scruple, drachma^†, ounce, pound, lb, arroba^†, load, stone, hundredweight, cwt, ton, long ton, metric ton, quintal, carat, pennyweight, tod^†.    [metric weights] gram, centigram, milligram, microgram, kilogram; nanogram, picogram, femtogram, attogram.    [Weighing Instrument] balance, scale, scales, steelyard, beam, weighbridge^†; spring balance, piezoelectric balance, analytical balance, two-pan balance, one-pan balance; postal scale, baby scale.    [Science of gravity] statics.    ... show more

Dutch: microgram
Polish: mikrogram, µg