The Collaborative International Dictionary of English v.0.48:

Farthing \Far"thing\, n. [OE. furthing, AS. fe['o]r[eth]ung, fr.
   fe['o]r[eth]a fourth, fe['o]r, fe['o]wer, four. See Four.]
   1. The fourth of a penny; a small copper coin of Great
      Britain, being a cent in United States currency.
      [1913 Webster]

   2. A very small quantity or value. [Obs.]
      [1913 Webster]

            In her cup was no farthing seen of grease.
                                                  --Chaucer.
      [1913 Webster]

   3. A division of land. [Obs.]
      [1913 Webster]

            Thirty acres make a farthing land; nine farthings a
            Cornish acre; and four Cornish acres a knight's fee.
                                                  --R. Carew.
      [1913 Webster]

WordNet (r) 3.0 (2006):

farthing
    n 1: a former British bronze coin worth a quarter of a penny

Moby Thesaurus II by Grady Ward, 1.0:

141 Moby Thesaurus words for "farthing":
   a continental, a curse, a damn, a darn, a hoot, ace, atom,
   bagatelle, bauble, bawbee, bean, bibelot, bit, brass farthing,
   button, cent, crown, curio, dab, dole, dollar, dot, dram, dribble,
   driblet, dwarf, farce, feather, fig, fiver, fleabite, fleck,
   florin, flyspeck, folderol, fourpence, fourpenny, fourth,
   fourth part, fragment, fribble, frippery, gaud, gewgaw, gimcrack,
   gobbet, grain, granule, groat, guinea, hair, half crown,
   half dollar, halfpenny, handful, hill of beans, iota, jest, joke,
   jot, kickshaw, knickknack, knickknackery, little, little bit, mag,
   meg, minikin, minim, minimum, minutiae, mite, mockery, modicum,
   molecule, molehill, monkey, mote, new pence, np, nutshell,
   one-fourth, ounce, p, particle, pebble, pence, penny, peppercorn,
   picayune, pin, pinch, pinch of snuff, pinprick, pittance, point,
   pony, pound, quart, quarter, quartern, quarto, quid, rap, red cent,
   row of pins, rush, scruple, shilling, shit, sixpence, smidgen,
   smitch, snap, sneeshing, sou, speck, spoonful, spot, straw, tenner,
   thimbleful, threepence, threepenny bit, thrippence, tiny bit,
   tittle, toy, trifle, trifling amount, trinket, trivia, triviality,
   tuppence, twenty-five cents, twenty-five percent, two bits,
   two cents, twopence, whim-wham, whit



Easton's 1897 Bible Dictionary:

Farthing
   (1.) Matt. 10:29; Luke 12:6. Greek assarion, i.e., a small _as_,
   which was a Roman coin equal to a tenth of a denarius or
   drachma, nearly equal to a halfpenny of our money.

     (2.) Matt. 5:26; Mark 12:42 (Gr. kodrantes), the quadrant, the
   fourth of an _as_, equal to two lepta, mites. The lepton (mite)
   was the very smallest copper coin.