dramyoudaoicibaDictYouDict[dram 词源字典]
dram: [15] Dram was borrowed from Old French drame or medieval Latin drama, which were variants respectively of dragme or dragma. Both came from drachma, the Latin version of Greek drakhmé. This was used in the Athens of classical times for both a measure of weight (hence the meaning of modern English dram) and a silver coin (hence modern Greek drakhmē), in English drachma [16].

It is thought to have originated in the notion of the ‘amount of coins that can be held in one hand’, and to have been formed from *drakh-, the base which also produced Greek drássesthai ‘grasp’. (Latin drachma is also the source of dirham [18], the name of the monetary unit used in Morocco and the United Arab Emirates.)
=> dirham, drachma[dram etymology, dram origin, 英语词源]
dram (n.)youdaoicibaDictYouDict
mid-15c., "small weight of apothecary's measure," a phonetic spelling, from Anglo-Latin dragma, Old French drame, from Late Latin dragma, from Latin drachma "drachma," from Greek drakhma "measure of weight," also, "silver coin," literally "handful" (of six obols, the least valuable coins in ancient Athens), akin to drassesthai "to grasp." The fluid dram is one-eighth of a fluid ounce, hence "a small drink of liquor" (1713); Hence dram shop (1725), where liquor was sold by the shot.