Obolus

from WordNet (r) 3.0 (2006)

obolus
    n 1: a Greek unit of weight equal to one tenth of a gram

from The Collaborative International Dictionary of English v.0.48

Obolus \Ob"o*lus\, n.;pl. {Oboli}. [L., fr. Gr. (?)] (Gr.Antiq.)
   (a) A small silver coin of Athens, the sixth part of a
       drachma, about three cents in value.
   (b) An ancient weight, the sixth part of a drachm.
       [1913 Webster]