sou \sou\, n.; pl. sousor. f. sou, of. sol, from l. solidus a
   gold coin, in ll., a coin of less value. see sold, n.,
   solid, and and cf. sol, soldo.
   an old french copper coin, equivalent in value to, and now
   displaced by, the five-centime piece 1/20 of a franc, which
   is popularly called a sou.
   1913 webster
see also:
sous sold solid sol soldo 

sou
     n : a former french coin of low denomination; often used of any
         small amount of money; "he hasn't a sou to his name"

93 moby thesaurus words for "sou":
   deutschmark, mark, reichsmark, a continental, a curse, a damn,
   a darn, a hoot, afghani, anna, bagatelle, baht, bauble, bean,
   bibelot, bit, brass farthing, button, cent, centavo, centime,
   conto, curio, dollar, dong, farce, farthing, feather, fig,
   fleabite, florin, folderol, franc, fribble, frippery, gaud, gewgaw,
   gimcrack, guilder, gulden, hair, halfpenny, hill of beans, jest,
   joke, kickshaw, kip, knickknack, knickknackery, kopeck, krona,
   krone, lira, milreis, minikin, mockery, molehill, peppercorn,
   peseta, picayune, pie, piece of eight, pin, pinch of snuff,
   pinprick, pistareen, pound, rand, rap, red cent, rial, row of pins,
   ruble, rupee, rush, shekel, shilling, shit, snap, sneeshing, sol,
   stiver, straw, toy, trifle, trinket, triviality, tuppence,
   two cents, twopence, whim-wham, won, yen