ClipArt ETC
"A small coin of ancient Greece, in later times of silver, the sixth part of an Attic drachma, equal to 2.5 cents; multiples and sub-multiples of this coin were also used, and pieces of the value of 5, 4, 3, 2, 1.5 oboli, and 1/2, 1/3, 11/4th of an obolus respectively are to be found in collections." — Winston's Encyclopedia, 1919

Obolus

"A small coin of ancient Greece, in later times of silver, the sixth part of an Attic drachma, equal…