The Collaborative International Dictionary of English v.0.48:

Drachma \Drach"ma\, n.; pl. E. Drachmas, L. Drachm[ae]. [L.,
   fr. Gr. ?. See Dram.]
   1. A silver coin among the ancient Greeks, having a different
      value in different States and at different periods. The
      average value of the Attic drachma is computed to have
      been about 19 cents (U. S. currency, ca. 1913).
      [1913 Webster]

   2. A gold and silver coin of modern Greece worth 19.3 cents.
      [1913 Webster]

   3. Among the ancient Greeks, a weight of about 66.5 grains;
      among the modern Greeks, a weight equal to a gram.
      [1913 Webster]

WordNet (r) 3.0 (2006):

drachma
    n 1: a unit of apothecary weight equal to an eighth of an ounce
         or to 60 grains [syn: dram, drachm, drachma]
    2: formerly the basic unit of money in Greece [syn: drachma,
       Greek drachma]