Quadrans

The quadrans (literally meaning "a quarter") was a low-value Roman bronze coin worth 1/4th of an as. The quadrans was issued from the beginning of cast bronze coins during the Roman Republic with three pellets representing three unciae as a mark of value. The obverse type, after some early variations, featured the bust of Hercules, while the reverse featured the prow of a galley. Coins with the same value were issued from other cities in Central Italy, using a cast process.
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(n.)
The fourth of a penny; a farthing. See Cur.
  

(n.)
A fourth part of the coin called an as. See 3d As, 2.
  

N M
fourth part| a quarter; 1/4 as| small coin| "farthing"