The Attic Greek drachma was a weight of 6 obols, Greek mina, or about 4.37 grams.
The Roman drachma was a weight of Roman pounds, or about 3.41 grams.
A coin weighing one drachma is known as a stater, drachm, or drachma. The Ottoman dirhem was based on the Sassanian drachm, which was itself based on the Roman dram/drachm.
The British Weights and Measures Act of 1878 introduced verification and consequent stamping of apothecary weights, making them officially recognized units of measurement. By 1900, Britain had enforced the distinction between the avoirdupois and apothecaries' versions by making the spelling different:
drachm now meant only apothecaries' drachms, which were of an apothecaries' ounce of 480 grains, thus equal to 60 grains
Modern unit of mass
In the avoirdupois system, the dram is the mass of pound or ounce. The dram weighs grains, or exactly grams. In the apothecaries' system, which was widely used in the United States until the middle of the 20th century, the dram is the mass of pounds apothecaries, or ounces apothecaries , and troy ounce. The dram apothecaries is equal to or, or exactly grams. "Dram" is also used as a measure of the powder charge in a shotgun shell, representing the equivalent of black powder in drams avoirdupois.
Unit of volume
The fluid dram is defined as of a fluid ounce, and is exactly equal to:
A teaspoonful has been considered equal to one fluid dram for medical prescriptions. However, by 1876 the teaspoon had grown considerably larger than it was previously, measuring 80–85 minims. As there are 60 minims in a fluid dram, using this equivalent for the dosage of medicine was no longer suitable. Today's US teaspoon is equivalent to exactly 4.92892159375 ml, which is also US fluid ounces, US fluid drams, or 80 US minims. While pharmaceuticals are measured nowadays exclusively in metric units, fluid drams are still used to measure the capacity of pill containers. Dram is used informally to mean a small amount of spirituous liquor, especially Scotch whisky. The unit is referenced by the phrase dram shop, the US legal term for an establishment that serves alcoholic beverages.
The line "Where'd you get your whiskey, where'd you get your dram?" appears in some versions of the traditional pre–Civil War American song "Cindy". In Monty Python's song entitled "The Bruces' Philosophers Song" there is the following line: "Hobbes was fond of his dram". In the old-time music tradition of the United States, there is a tune entitled "Gie the Fiddler a Dram", "gie" being the Scottish dialectal version of "give", brought over by immigrants and commonly used by their descendants in Appalachia at the time of writing. In the episode "Double Indecency" of the TV seriesArcher, the character Cheryl/Carol was carrying around 10 drams of Vole's blood and even offered to pay for a taxi ride with it. In Frank Herbert's Dune, the Fremen employ a sophisticated measurement system that involves the drachm to accurately count and economize water, an ultra-precious resource on their home, the desert planet Arrakis.
